Contents Introduction Principles classification History Types of head gear uses Biomechanics of headgear Clinical applications Effect of treatment with headgears Protraction face mask Types of facemask Biomechanics of facemask
Extraoral appliances or orthopedic appliances are used to modify the growth of maxilla and mandible using extraoral forcesThey are appliancersquos that provide a means of applying anterior posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source
bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash
bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery
bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery
bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws
bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-
(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction
bull This seminar discusses the essential aspects of orthopedic appliances
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
bull There are 2 types of forces used in orthodontics-
1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement
2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Contents Introduction Principles classification History Types of head gear uses Biomechanics of headgear Clinical applications Effect of treatment with headgears Protraction face mask Types of facemask Biomechanics of facemask
Extraoral appliances or orthopedic appliances are used to modify the growth of maxilla and mandible using extraoral forcesThey are appliancersquos that provide a means of applying anterior posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source
bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash
bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery
bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery
bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws
bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-
(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction
bull This seminar discusses the essential aspects of orthopedic appliances
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
bull There are 2 types of forces used in orthodontics-
1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement
2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Extraoral appliances or orthopedic appliances are used to modify the growth of maxilla and mandible using extraoral forcesThey are appliancersquos that provide a means of applying anterior posterior or vertical directed forces to the dentition and skeletal complex from an extra-oral source
bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash
bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery
bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery
bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws
bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-
(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction
bull This seminar discusses the essential aspects of orthopedic appliances
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
bull There are 2 types of forces used in orthodontics-
1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement
2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
bull There are essentially 3 alternatives for treating any skeletal malocclusion ndash
bull (i) growth modificationbull (ii) dental camouflagebull (iii) orthognathic surgery
bull Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery
bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws
bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-
(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction
bull This seminar discusses the essential aspects of orthopedic appliances
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
bull There are 2 types of forces used in orthodontics-
1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement
2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
bull Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws
bull There are 3 types of orthodontic appliances that can be used for modifying the growth of maxillamandible-
(i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction
bull This seminar discusses the essential aspects of orthopedic appliances
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
bull There are 2 types of forces used in orthodontics-
1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement
2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
bull There are 2 types of forces used in orthodontics-
1) orthodontic force ndash when applied brings about dental change They are light forces ( 50-100 gm) bringing about tooth movement
2) orthopedic force ndash when applied brings about the skeletal changes They are heavy forces ( 300-500gm) that bring about changes in the magnitude amp direction of bone growth
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude
Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude amp direction of the jaws by modifying the pattern of bone apposition at periosteal sutures amp growth sites
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Principles or Orthopedic appliances
1) Magnitude of force ndash
bull Extra oral forces of much greater magnitude in excess of 400gms per side is required to bring about skeletal changes
bull Most orthopedic appliances employ forces in the range of 400-600 gm per side to maximize skeletal effect
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Kloehn suggested the use of frac34-3pounds of force armstrong and watson showed the use of 2-6 pounds of force
would bring about skeletal relationship changes Closson prescribed light and intermittent forces on the
molar he felt the younger the patient the lesser the pressure to be applied
Baldridge when doing clinical tests on the efficiency of the appliance carried out 1-2 pounds of force
Rickkets( 1979) force of 150 grms was appropriate for extraoral retraction in adults and children500 gm was required for orthopeadic change
Armstrong M M Controlling the magnitude direction and duration of extraoral force AM J ORTHOD59 217-243 1971
Watson W G A computerized appraisal of the high-pull face bow AM J ORTHOD 62 561 1972
Kloehn S J Guiding alveolar growth and eruption of teeth to reduce treatment time and produce a more balanced denture and face Angle Orthod 17 1033 1947
Baldridge unilatral traction with headcap angle orthod 3163681961
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
McLaughin Bennet and Trevisi (2001) recommended a force level of 250- 350 to provide anchorage for fixed appliances
In combination system- 100grm cervical pull with 150grm high pull for anchorage
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
2) Duration of force ndash
bull Orthopedic changes are best produced by employing intermittent heavy forces
bull Intermittent forces of 12-14 hours duration per day appear to be effective in producing orthopedic changes
bull An intermittent heavy force is less damaging to the teeth and periodontium than a continuous heavy force
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Poulton stressed on the point that the appliance should be worn atleast 12 hours a day
Armstone and watson suggested 22- 24 hours a day
Kloehn suggested 12-14 hours a day
Poulton changes in class II malocclusion with and without headgear therapy Angle orthod 29 232-2501950
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Direction of force ndash
bull Orthopedic force should be applied in the appropriate direction to have a maximum skeletal effect
bull The desired changes are best achieved when the line of force passes through the center of resistance of the skeletal structures to be moved
bull The force direction or force vector should be decided depending on the clinical needs
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
4) Age of the patient ndash
It is advisable to begin orthopedic appliance therapy while patient is still in the mixed dentition period to make most of the active growth occurring prepubertal growth spurt
Treatment may have to be continued until the completion of adolescent growth so as to prevent relapse caused by the re-expression of patients fundamental growth pattern after cessation of orthopedic therapy
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Kloehn and closson preferd to commence treatment in the early mixed dentition stage at the age of 4- 6 years
Lucchesse (1960) mossman and hackensack parker put emphasis on starting the treatment before the pubertal growth spurt 10-14 years
Graber block and Fisher suggested treatment in the mixed dentition itself because incidence of root resorption was lowered in this stage of dentition
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
In contrast to all these suggestion concerning mixed dentition Fletcher in Dental practitioner stated ldquothe arrival of the full dentition provides the orthodontist with firmer and more extensive anchorage against which multiple tooth movements can be carried outrdquo
Fletcher the age factor In orthodontics 1958
Lucchese indications for the use of orthodontic appliances exerting extra-oral force 1960
GraberOrthodontic forces- facts and fallacies Amj Orthod 1955
Block Headgear-modifications and admonition1954
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Types of extra oral appliance
The following are the commonly used orthopeadic appliances
Head gear Reverse pull facial mask Chin cup
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
History Weinberger in his book ldquoOrthodontic review
evolution and progressrdquo reported JS Gunnel used the occipital anchorage at around 1822-23
The head gear was popularised for retraction of upper protruding incisors by Norman kingsley in 1855
Bien also reported Kingsley using the headgear to depress and drive ant teeth distally after the extraction of first promolars
Angle in 1889 in his text book on orthodontia discussing occipital anchorage stated that this means of anchorage was becoming more popular for cases of maxillary protrusion
Later however after Angle started using inter maxillary elastics for the correction of Class II malocclusions and he changed his stance on Extra oral appliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
In 1898 guilford talked about directional pull by activating rubber strands of the ldquoskull caprdquo above or below the ear
As orthodontics progressed in the early twentieth century however extraoral appliances and mixed dentition treatment were abandoned as they were termed an unnecessary complication
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Oppenhiem from vienna in 1936 revived the idea that headgear would serve as a valuable adjunct to treatment after his experimental treatment approach to an actress who rejected visible appliances
The result was so rewarding that he continued this approach and brought it to the US
He used the headgear to uncrowd teeth and to correct class II maloclusions without having to extract teeth
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
In his paper in 1936- oppenhiem says about the occipital anchorage-rsquo for the treatment of similar caseswhich form a great portion of our practice material and which deal with a forward wandering of the buccal teeth especially the canines and also in the treatment of class II cases in which we carry the upper teeth backward rather than the lower teeth forward this procedure is in my opinion most reccomendablerdquo
Biologic orthodontic therapy and reality Angle ortho 6157-167 1936
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Much credit must be given to Kloehn for reviving the use of extra oral appliances
He went on to combine the dental bow and facebow in a soldered joint
He also introduced the elastic neckstrap to apply traction
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
High pull headgear also became famous to
a)Prevent mandibular rotationb)Attached to upper incisors to keep
them intruded and torqued while retracting them
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Rickets stopped using the high pull headgear in 1950s claiming they were very slow in class II correction and they also did not prevent dolichocephalic patterns of facial growth
Rickets observation with cervical headgear were-a)there was retraction of maxillary complex measured at point A
b)There was minimal extrusion of upper 1st molars and incisors c)The palate rotated in a clockwise directionThe occlusal plane rotated in anticlockwise directiond)minimal or no adverse rotation of the mandible Ricketts the influence of orthodontic treatment on facial
growth and development 1960
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
In 1955 graber in his article ldquoextraoral force facts and fallaciesrdquo quoted
a)There is no evidence that maxillary growth per se is affected
b)Bodily distal movement of molars can be accomplished but in most cases it is merely restrained from coming forward in its normal path or tipped distally
c)It is possible to impact 2nd molars temporarily by excessive distal tipping of first molars
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
d)Marked improvement in basal relation can be obtained
e)Growth is an important factor its presence or absence profoundly influences the results Coordination of treatment with pubertal growth spurt means a greater likelihood of success
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Classification of headgear Cervical pull High pull Combination Interlandi J-hook Asymmetricunilatral Reverse pull head gear
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Appliance designBasic element Force delivering unit ie facebow lsquoj-
hooksrsquo Force generating unit ie Elastic
springs Anchor unit ie Head cap neck pad
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Face bows made of stainless steel having a diameter between 0040rdquo to 0050rdquo It engages buccal tubes on the first molars The methods used to make the inner bow stop mesial to the 1st molar are
Bayonet bends horizontal inset bends which prevent the anterior portion from impinging on brackets on teeth
Stops cylindrical tubes with an internal diameter corresponding to inner bow diameter
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Preformed inner loops serve as adjustable stops as well as shock absorbers and are angulated for clearance
The also facilitate necessary unilateral adjustments to keep the facebow length as molars gradually move distally and reduced facebow length as incisors are retracted
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Outer bow (wisker bow) Acts as a media through which force is
transmitted to the inner arch Dentaurum products have a standard bilaterally symmetrical facebow in which the joint between the inner and outer bow can come with or without cuspidhooks and in 3 sizes- short medium and long
Outer bow dimension -0051rsquo- 0062rsquo stainless steel contoured to the check contour with the inner and outer bow joint lying between the lips when the inner bow engages the buccal tube
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The outer bow can be short medium or long
Short ndash outer bow is lesser in length than inner bow
Medium ndash outer bow length is equal to inner bow
Long ndash outer bow is longer than inner bow
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Miscellaneous components Springs calibrated tension springs are
available These have the advantage that the applied force can be varied
Elastics serve as force elements and are available in the following forms
neck bands with strongmedium pull extra-oral plastic chains with length 119mm
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Friction release systems these include safety release to reduce ldquosling-shotrdquo hazards by means of clips which release automatically when pulled with excessive force they provide case of assembly and include an inner steel coil to provide a consistent traction force
Prescription tab variable force neckpads these provide adjustable calibrated force of 4-18 oz
Headcaps of the following types are available preassembled standard universal preassembeld extra comfort vertical pull
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Cervical pull headgear Introduced by Kloehn in 1947 it is also known as
the kloehn headgear This was to become the most widely used form of
an extraoral traction appliance to be used in contempopary orthodontics
>
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Since the anchor unit (neck strap) passes around the patients neck and is attached to the outerbow to produce a force acting 5o-10o tangent the occlusal plane it is called the cervical pull headgear
Recommended time of wear is 12-14hrsday this disto occlusally directed force has an extrusive effect on the molars
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
High pull head gear The high-pull facebow is attached to
the maxillary first molars by means of an outer bow
>
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The outer bow is bent upwards so that the point of force application and the direction of force lies above the centre of resistance of the maxillary first molarsthe inner bow lies passively in the molar tubes or it can be expanded if an increase in transpalatal width is desired
Rationale justifying the use of a high-pull headgear-
Cervical pull headgears have certain drawbacks that are especially undesirable in a majority of class II division1 cases
These problems have their origin in the line of action of the force generated by a cervical-pull extraoral traction device which often passes below the centre of resistance of the maxillary first molar
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
As a result of this it produces a moment of force which results in the mesial tipping of the roots and a distal crown inclination of the posterior maxillary buccal segment
An additional drawback of the cervical pull heargear is the disto-occlusal orientation of generated force which causes extrusion of molars this prevents its use in patients its use in patients having a high mandibular plane angle
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The tendency of the cervical-pull headgear to cause the tipping and extrusion of molars might compromise the stability of the orthodontically corrected dentition
Sothe concept and utility of high-pull headgear was put forth where the resultant force was directed through the level of trifuriation of maxillary molars in a postero-superior direction
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
With the high-pull headgear it is possible to change the direction of force in relation to the centre of resistance of the dental units to which force is being applied in order to achieve better control of resulting tooth movement in a distal direction
And to modify vertical changes in the maxillary molar position to correct class II relationships using a relatively lower magnitude of forces
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Treatment effects of the high-pull headgear include
intrusion and distalization of maxillary molars
Anti-clockwise mandibular rotation Decreased lower facial height Retrusion of incisors
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Interlandi type headgear The interlandi type high pull
headgear In this design the outer bows
are attached to the head straps of the headgear with the help of frac12rsquo latex elastics
the direction of the applied force was modified by changing the point of attachment of these elastics
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
In order to prevent the distal tipping of molars the end of the outer bow must terminate in the same plane as the centre of resistance of the upper first molar
The inner bow is made parallel to the occlusal plane and the length of the outer-bow is reduced so that it does not extent distal to the maxillary first molar
a force of 500gmsside is used with recommended wear of 12 hrsday
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Combination facebow The cervical facebow and the high pull facebow
can be used in combination to alter the direction of force along the plane of the occlusion
Advocated by arm strong(1971) and berman(1976)
>
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
J-hook headgear The forces produced by extraoral traction
also can be attached anteriorly by means of j-hooks to the archwire or the hooks soldered to the archwire
Flared maxillary incisors can be retracted using either a high pull or a straight-pull headgear combined with j-hooks that are attached to the arch wire anteriorly or by using a closing arch supported by headgear
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Headgears with j-hooks also are used to potentiate arch wire mechanics by helping control forces incorporated into the archwire(eg torque intrusion)
J hooks can be applied to the maxillary teeth in a variety of force vectors to retract and intrude the maxillary incisor teeth
Usually done in edgewise mechanotherapy
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Armstrong(1971) hickham(1974) and vaden et al (1986) have used J hooks with the interlandi headgear to simultaneously retract maxillary and mandibular canines
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Asher face bow demonstrated by roth
This is a high pull facebow with a headcap and a short intra oral bow
Used to retract maxillary incisors in premolar extraction spaces using 2-6 ounces of force
It applies force directly to maxillary canine brackets
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Advantages Comfortable to wear Conserves anchorage Simultaneous retraction of both arches
helps in intrusion of incisors
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Similar lsquoEn-massersquo retraction of the anterior arch was done by Enis Guray et al (1997)
They used the interlandi type headgear with a modified anterior segmental facebow from canine to canine
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Assymetricalunilateral headgears
Orthodontic treatment often requires an extraoral force that will predictably deliver a greater distal force to one side of dental arch than to the other(eg class II molar relationship on one side class I on the other)
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The centre of attachment to the inner bow is moved laterallythus producing asymmetrical forces against the two sides of the dental arches
Disadvantage-extended use of this device will tend to skew the arch to one side
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Power arm facebow-one outer bow is longerwider than the otherlongerwider bow tip is located on side anticipated to receive greater distal force
Power arm facebow also generates lateral forces which tend to move the favored molar tooth into lingual crossbite and the opposite molar into buccal crossbite
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Soldered offset facebow- outer bow is attached to inner bow by means of a fixed soldered joint placed on the side favored to receive greater distal force
Swivel offset facebow-in this design outer bow is attached to inner bow by means of a swivel joint located in an offset position in the side favored to recive greater distal force
Said to minimise undesirable lateral force
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Biomechanics Centre of resistance- when
a force is applied too a body the body resists the force (Newtons third law of motion) If it is a free body this resistance to movement can be reduced to one point called the centre of resistance A force directed through the centre of resistance will translate the body
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Centre of rotation-The centre of rotation is the point about
which the object rotates This varies with the location of the centre of resistance and the force applied to the object
Pure rotation occurs when the centre of rotation is at the centre of resistance
Pure translation occurs when the centre of rotation is at an infinite distance away from the centre of resistance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Location of the centre of resistance
a)Maxillary first molar- situated at trifurcation of the roots
Dermaut LR Kleutghen JPJ De Clerck HJJ Experimental determination of the center of resistance of the upper first molar in a macerated dry human skull submitted to horizontal headgear traction Am J Orthod Dentofacial Orthop 19869029-36
b)Single rooted tooth- situated at the 33 of the root length apical to the alveolar crest
Burstone CJ The biomechanics of tooth movement In Kraus BS eds Vistas in orthodontics Philadelphia Lea amp Febiger1962 p 197-213
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Maxillary dental arch- between the roots of 1st and 2nd premolars
Maxillanasomaxillary complex- nanda and goldin (1980) reported it to be in central part of zygoma
According to billetet al(2001) it is same as maxillary archTanne et al (1995) ndash at pterygo-maxillary fissure
For 4 maxillary incisors- according to matsui et al (2000) it is located within the mid-sagittal plane approximately 6-mm apical and 4-mm posterior to a line perpendicular to the occlusal plane from the labial alveolar crest of the central incisor
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Centre of resistance of the maxilla- posterior superior aspect of the zygomaticomaxilary suture ndash stockli and tussherre
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Greenspanrsquos study Greenspan in his study in 1970 gave
reference charts for clinical use simplifying the direction of pull of the head gear in accordance with different lengths of the outer bow and its actions
His analogy of the tooth movement was that of a flywheel which revolved around a fixed axisand was affected by different directions of force
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Cervical headgear
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
When the outer bow lies along the lfo no moment occurs and the force system will be reduced to a bodlily movement in a posterior and extrusive directionouter bow is equal length to inner bow
If the outer bow is placed above this lineit passes distal to centre of resistancethe moment produced by the force will be in countreclockwise directionouter bow is long
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
If the outer bow is adjusted below this line the moment created will be clockwisehowever the direction of the forces are the same-extrusive and posteriorit tends to steepen occlusal plane in such cases
If the outer-bow is located below the neckstrap the resultant force will be small intrusive one instead of extrusive ofcourse a distal force and large clockwise moment will also be produced
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The directional pull provided by the cervical headgear is especially advantageous in treating short-face class II maxillary protrusive cases with low mandibular plane angles and deep bites where it is desirable to extrude the upper posterior teeth
Also the clockwise moment that is so readily produced with this headgear is very effective in helping conserve anchorage in extraction cases
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
High pull headgear
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
This style headgear always produces an intrusive and posterior direction of pull due to the position of the headcap
The direction of the moment that is produced is dependent on the position of the outerbow
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
If the outerbow is placed anterior either above or below the occlusal plane level the moment produced will be counterclockwise
On the other hand if the outer bow is placed posterior to this line the moment produced will be in clockwise direction
The magnitude of this moment will be proportional to the distance of the outer bow to CR
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
If a distal and intrusive movement with no moment is desired the outer bow must be placed somewhere along centre of resistance
This force system would be beneficial in a long-face class II patient with high mandibular plane angle where intrusion of maxillary molars would decrease facial height and improve the facial profile
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Straight pull Occipital headgear
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
This style headgear is a combination of highpull and cervical headgear with the advantage of increased versatility depending on the force system desired the orthodontist has the opportunity to change the location of the line of force
The prime advantage of this headgear is its ability to produce an essentially pure posterior translatory force
This is accomplished by placing the Line of force through the centre of resistance parallel to the occlusal plane clinically this means bending the outer bow to the same level as CR and hooking the elastic to a notch at the same vertical level
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The relation of the outer bow to the Line of force dictates the direction and magnitude of forces and moments
Placing the outerbow above the Line of force will produce a posterior forcecounter clockwise rotation and most often intrusive force
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
If the outer bow is below the Line of force the force produced will be posterior and superior and the moment will be in a clockwise direction
The straight pull headgear is the appliance of choice in a class II malocclusion with no vertical problems it is also the headgear of preference when the main thrust of headgear wear is to prevent anterior migration of maxillary teethor possibly even translate them posteriorly
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Vertical pull headgear The main purpose of this headgear is to
produce an intrusive direction of force to maxillary teeth with posteriorly directed forcesif the outer bow is hooked to the headcap so that the line of force is perpendicular to the occlusal plane and through the CR pure intrusion may take place
The vertical-pull headgear is not commonly used as are the othershowever it is very useful when pure intrusion of buccal segments is required as in the class I open-bite patient
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Treatment effects Extra oral traction has been shown to
produce a variety of skeletal and dento alveolar effects in class II patients
Even though there is some agreement among investigators as to the effects produced the clinical management of the appliance the direction of force applied and the amount of force used may explain some of the differences among investigation
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Anteroposterior dimension Maxillary skeletal positionA primary treatment effect of extraoral traction is the
restriction of maxillary skeletal growththere is virtually a universal agreement that because of treatment point A is repositioned posteriorly relative to the remainder of the face resulting in a reduction in maxillary prognathism
Wieslander(1974) has shown that this technique also influences the cranial base by producing a counterclockwise tilting of the spheno-ethmoid plane during 3-4 years of treatment with a headgear
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Maxillary dentoalveolar position
Distal movement of the maxillary molars is a typical effect produced by cervical headgear therapy in contrast Hubbard and co-workers (1994) who studied a sample of patients treated by kloehn reported a mesial movement of the first molar
Extrusion of the maxillary molars also has been observed with two to three times as much extrusion reported as would be expected during normal growthon the other hand Hubbard and colleagues did not observe molar extrusion
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Mandibular dentoalveolar position
There is virtually no literature that addresses the effect of the cervical-pull facebow on the mandbular dentition other than the treatment effects that are produced in association with fixed appliance treatment there appears to be no effect
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Mandibular skeletal position The antero-posterior relationship of the chin has
been correlated to the amount of vertical opening produced during treatment A downward and backward rotation of the mandible and a similar movement of point B and pogonion have been reported as has an opening of the mandibular plane angle
Kloehn(1947) ringenberg and butts(1970) report no change in the SNB anglebut other investigators (mcnamara 1996 Graber 1956) note a posterior movement of point B
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Vertical dimension There is no universal agreement as to
the effect of cervical headgear treatment on the vertical dimension as investigators have differed in describing the effect of this type of therapy on the various aspects of vertical facial measures
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Mandibular plane angle and lower anteror facial hieght
An increase in the mandibular plane angle as the mandible is hinged open has been reported by many investigators
An opening of the bite and an increase in lower anterior facial height also has been a frequent finding Klien(1956) report that extraoral force tends to open the Y axis angle and lengthen the face more than would occur with normal growth
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
A high pull headgear has been recommended to reduce the extrusion of the maxillary first molars
In contrast ringenberg and butts (1970) baumrind (1978) and hubbard and coworkers (1994) report a closure of the mandibular plane angle with treatment where as others reported no change
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Occlusal plane angle Investigators have differed as to the effect of
extraoral traction on the orientation of the occlusal plane relative to the cranial base
The anatomic occlusal plane normally closes with age Klien(1957) King(1957) and Hubbard et al (1994) reported that the angle of the occlusal plane remain unchanged relative to the cranial base
Hubbard et al noted that the functional occlusal plane closed slightly with treatment he stated it became more or less parallel to the s-n plane
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Palatal plane angle The palatal plane has been shown to
tip anteriorly with an uneven descent resulting in the anterior nasal spine tipping more inferiorly than the posterior nasal spine
On the other hand Kloehn(1961) and Boecler and co-workers (1989) noted no change in the palatal plane
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Transverse dimension In the literature changes in the transverse
dimension with extra oral traction has been minimal
Ghafari et al (1994) who conducted a comparative study of the straight- pull headgear and FR-2 appliance of frankelThe inner bow of the facebow was adjusted at every appointment rdquoto avoid any constriction or major expansion of the intermolar distancerdquoresulting in a total expansion of the inner bow of 15-20mm
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Ghafari et al noted increases not only in intermolar distance but in inter canine distance as well
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Stienberg Burstone Anderson( angle orthod 2004) did a study to see whether high pull headgear can prevent steepening extrusion of buccal segments during incisor retrusion and whether it can increase the rate of incisor intrusion
Results showed that high pull headgear has no effect on extrusion of buccal segments during incisor retrusion nor any effect on rate of intrusion
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Haulabakis et al (ajo 2004) studied the effect of cervical headgear on patient with high or low mandibular plane angle and assessed the ldquomythrdquo of posterior mandibular rotation
They concluded that regardless of treatment taken vertical skeletal relationship was not affected
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Leandro et al (AJO 2005) studied the effects of cervical headgear on space available for maxillary 2ndmolar to erupt
They suggested that despite restriction of movement of maxillary 1st molar and maxilla there was sufficient space for 2nd molar to erupt because of posterior displacement of PTM point and growth at maxillary tuberosity
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Hubbard et al(angle 1994) studied the effects of orthodontic treatment with the use of cervical headgear in class II malocclusion patients
Overall the results showed changes were very close to what would occur as a result of normal growth in class I individuals
Maxillary 1st molars continue to grow forward cranial base showed very little change
Mandibular plane angle did not increase appreciably with treatment
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Brite melsen (AJO 1978) have reported that influence of headgear on growth pattern of facial skeleton was reversible
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Headgear with activator
Pfeiffer attached the HG directly to the activator and applied occipital traction to achieve better vertical and rotational control during class II treatment
Bass modified the appliance and used a J hook headgear
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
The primary treatment objective is to restrict the developmental contributions that tend to cause a skeletal class II and at the same time attempt to correct antero posterior relation of jaws
Usage mainly limited to mixed dentition with force application of 250 grmsside
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Head gear with herbst appliance
First decribed by Wieslander (1984) Wherein the headgear is fixed to a tube soldered to the molar attachment
High pullforce direction using 100 gmsside of force and worn for 12-18 hrsday in mixed dentiton period
Produces a synergestic effect on correction of skeletal class II cases wherein the herbst appliance stimulates mandibular growth while this headgear force redirects maxillary growth
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Clinical Implications There are three main uses of headgear
force 1 Anchorage control2 Tooth movement3 Orthopedic changes
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Anchorage control In class II treatment headgear force can
play a major role in ensuring that buccal segment teeth do not move mesially when anteriors are retracted
Intraoral mechanics often result in eruption of teeth
Headgear produces a vertical force greater than the force of side effect
Inner and outer bows can be of any shape convolution and length
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Tooth movement Adjustment of outer bow such that a horizontal
force is produced that passes through the center of resistance of maxillary first molar and the patient wears the headgear at a level of 14 hours each night consistently clinical experience shows that the first molars will move distally 2mm in 24 months without tipping
Distal tipping is not preferred as finite element studies have shown that the stress levels at the periodontal ligament-bone and tooth interfaces are beyond acceptable limits even when tipping forces are very light
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Intrusion in deep bite cases Headgear can be used in adjunct to upper utility arch
High pull headgear allows more intrusive control permitting maximal incisor movement whilst minimizing possible molar tipping and also used to deliver orthopedic force on developed premaxillary segment
120 to 150 g force is deliveredDistalization of molars Headgear is the obvious choice Fill time wear is
necessary Molar extrusion should be avoided so straight pull or high pull is used and not cervical
Force ndash 300g on each side Unilateral molar distalization in unilateral class II can be
achieved by asymmetric cervical headgear
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Orthopedic changes If the headgear is applied
through the center of resistance of maxilla which is in the posterosuperior part of zygomaticomaxillary suture
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
If a preadolescent patient wears the headgear at least 12 hours each night the forward component of maxillary growth is redirected
Cervical traction produces stresses along the frontal process of maxilla zygomaticofrontal suture and the junction of the palatine bones areas where high-pull traction produced no observable effect Only the high-pull headgear produces stress at the anterior junction of maxillae (anterior nasal spine)
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Pterygoid plates of the sphenoid High stress develops upon activation These stresses begin in the middle of the posterior
curvature of the plates and just superior to their anterior junction with the palatine bone and maxilla
As the force increases the stresses progress superiorly toward the body of the sphenoid bone
Zygomatic arches Cervical and high pull both produce similar stress Starts at the inferior border of the
zygomaticotemporal suture and proceeds posteriorly along the zygomatic process of temporal bone
Cervical force produces more intensity at lower load level
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Junction of the maxilla with the lacrimal and ethmoid bones
Both cervical and high pull produce a stress concentration at the junction of the maxilla with the lacrimal bones and with the orbital plates of ethmoid
Maxillary teeth High stresses around maxillary molars with
cervical traction These located around the middle third of the mesiobuccal root and around distobuccal root at a position toward apex
Also distal to second molar
Frontal process of maxilla Stresses produced anterior to nasolacrimal
foramen only with cervical pull
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Palate Cervical traction produces stress in posterior
region developing in the horizontal portion of palatine bones High pull has no effect
Anterior junction of left and right maxillae Only high pull produces forces below the anterior
nasal spine and just lateral to the suture between the two maxillae
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Sphenomaxillary suture- large compressive stresses
Temporozygomatic suture- tensile normal stresses Sphenozygomatic suture- large tensile stressesFrontozygomatic suture- large compressive stressFrontomaxillary suture- large tensile stress Sphenomaxillary and sphenozygomatic sutures
in particular resisted the posterior displacement of the complex
Stresses in the nasomaxillary sutures are varied by the direction of headgear force and the force applied in the direction closest to that of the CRe may produce the most effective sutural modification for controlling maxillary growth
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Maxillary protraction with mandibular growth restriction
The appliance should be simple and mechanically sound enough to be used as a therapeutic procedure for treatment of prognathic syndromes maxillary retrutions clefts amp mandibular prognathism
HICKHAM (1972) claims he was the first to use a reverse headgear However this modality was made popular by DELAIRE around the same time
Delaire Verdon and Floor have extensively used a facial mask to protract the maxilla anteriorly Elastics generating forces of 1000 to 2000 Gm are used from distal of the maxillary molars to the wires of the mask to move the maxilla anteriorly
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Armstrong applied 500 Gm of force via chin cups on 100 adolescent patients with mandibular prognathism He reported that half of his patients showed improvement in the Class III profile whereas none of the control nontreated patients showed any favorable change
Graber and Chung reported results in patients treated with chin cups for 12 to 14 hours each day with a force of 15 to 2 pounds on each side They showed that mandibular growth could be redirected with a chin cup They asserted that continuous use of the appliance for a long period or through active growth was necessary to achieve stable results
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Nelson described an appliance which used anterior pull on the maxilla by means of a football-type helmet Haas showed downward and forward movement of the maxilla as a result of palatal expansion The maxillary effect was enhanced by the use of Class III elastics from a chin cup to the distal aspect of the palatal appliance
Several clinical studies in the past have noted that treatment of patients in skeletal Class III should include protraction of the maxilla with or without chin cups Graber noted that restriction of growth or distal movement of the mandible was impossible
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Indications1 Growing patients having a prognathic mandible
and a retrusive maxilla ( class III malocclusion)2 For selective rearrangement of the palatal
shelves in cleft patients
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Sites of anchorage Anchorage from chin force is transmitted
to the condylar cartilage amp thus alters the growth of mandible
Anchorage from skull disadvantage include patient discomfort while sleeping cost and time required in fabrication and fixing
Anchorage from chin amp forehead no excessive force is exerted onto the growth cartilage Disadvantage is difficulty in speech amp compromise in aesthetics amp comfort
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Biomechanical considerations
1 Amount of force- the amount of force required to bring about skeletal changes is about 1 pound or 450 gms per side
2 Direction of force- 15 ndash 20 degree downward pull to the occlusal plane to produce a pure forward translatory motion of the maxilla If the line of force is parallel to the occlusal plane a forward translation as well as an upward rotation takes place
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
3 Duration of force- time taken to achieve desired results is proportional to the amount of force utilized Low forces (250 gm side) take 13 months to produce desired results High forces ( 1600- 3000 gms) reduced treatment time to 4 ndash 21 days
4 Frequency of use- 12 to 14 hours of wear a day
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Parts of a reverse pull headgear
1Chin cup is used to take anchorage from the chin area It can be ready made or can be fabricated from an impression of the patients gonial region It is
connected to the rest of the face mask assembly by means of metal rods
2 Forehead cap use to derive anchorage from the forehead
3 Elastics used to apply a forward traction on the upper arch Vertical posts of the chin cup are used to attach the elastics onto the molar tubes or hook soldered on the arch wire It is purely for tooth movement
4 Intraoral appliance traction hooks are placed either in the molar or premolar region
5 5 Metal frame It connects the various components such as the chin cup and forehead cap It also has provision to receive elastics from intraoral appliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Also called as ldquoprotraction headgearrdquo When an anterior protractory force is required a protraction
headgear is used Principle ndash pulling force on the maxillary structures with reciprocal
pushing force on the forehead or mandible through facial anchorage
A reverse pull headgear basically consists of a rigid framework which takes anchorage from chin or forehead or both for anterior traction of maxilla using extra oral elastics that generate large amounts of force up to 1 kg or more
>
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Types 1 Protraction headgear by Hickham Uses the chin and top of the head for anchorage Force distribution is ndash 15 head 85 chin Consists of 2 short arms in front of the mouth to engage
maxillary protraction elastics 2 long arms run parallel to the lower border of the mandible amp
go vertically up from the angle of the mandible and end behind the ears
An elastic strap is attached to the end of the long arms to encircle the head
Advantages ndash 1) better aesthetics 2) comfort 3) option of unilateral force applicability
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
2 Face mask of Delaire Uses the chin and forehead for
support
Appliance is made up of a rigid wire framework which is squarish amp kept away from the face
It has a forehead cap and a chin cup with a wire running in front of the mouth used for elastic attachment
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Tubinger model
Modified type of Delaire face mask
Consists of a chin cup from which originates 2 rods that run in the midline amp is shaped to avoid the interference of nose
The superior ends of the 2 rods house a forehead cap from which elastics
encircle the head
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
4)Petit type of face mask
Modified Delaire face mask
Consists of a chin cup amp a forehead cap with a single rod running in the midline from forehead cap to chin cup
A crossbar at the level of the mouth is used to engage elastics
Advantage ndash forehead cap chin cup amp the cross bar can be adjusted to suit the patient
An Orthopedic Approach to the Treatment of Class III Malocclusion in Young Patients
VOLUME 21 NUMBER 09 PAGES (598-608) 1987JAMES A MCNAMARA JR DDS PHD
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Influence of rapid maxillary expansion used with protraction HG (considered as non-surgical distraction osteogenesis)
Evidences Baccetti et al (1998) Significant skeletal effects of early
treatment of Class III malocclusions with maxillary expansion and face-mask therapy
Kim et al (1999) A meta-analysis of the effectiveness of protraction facemask therapy Patients who did not have palatal expansion had longer treatment times and ended up with more upper incisor proclination - ie more dental change and less skeletal change
Franchi et al (2004) concluded that it was possible to achieve a 2 mm advancement of the maxilla that would withstand the active growth period if RME and protraction head gear was undertaken in the deciduous dentition or early mixed dentition
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Type of screw -HYRAX
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Technique1 fabricate and bondcement the rapid maxillary expansion appliance2 Appliance is activated once per day until the desired increase in maxillary
width has been obtained3 If patients do not need an increase in maxillary width the appliance is still
activated for 7-10 days to disrupt the maxillary sutural system (Haas 1965)4 then protraction headgear is fitted5 A heavy orthopaedic force of 400g per side is applied to the maxillary
complex6 Force vector should be 15-30 degree below the horizontal7 The patient wears the facial mask for at least 12-14 hours per day8 Active treatment should be limited to 9-12 months because of the risk of
decalcification of the dentition9 Retention with a number of appliances acrylic maxillary retainer FR-3
appliance or a chin cup (seldom used)10 Patient should be warned of the possibility of orthognathic treatment if
growth is unfavorable11 Labial root torque Most class 3 patients demonstrate considerable proclination of
the upper labial segment at the end of treatment Catania et al (1990) recommend in his case report to use inverted U incisor bracket to counteract the effect of proclination
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Modification In 2005 Eric Liou et al introduced the
concept of ALT-RAMEC alternate rapid maxillary expansion and contraction
They stated that 5 weeks of ALT RAMEC opened the circumaxillary sutures more than RMELiou E J and W C Tsai A new protocol for maxillary protraction in cleft patients repetitive weekly protocol of alternate rapid maxillary expansions and constrictions Cleft Palate Craniofac J 2005 42121ndash127
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Skeletal and Dental effects of FaceMask therapy
Forward movement of maxilla and point A Reduction in mandibular projection
satisfactory maxilla-mandibular relationship According to Mcdonald et al Bacetti et al
Sinclaire et al ndash there was a counterclockwise rotation of the maxilla
Reverse overjet in anteriors was seen Improvement in molar relationship Downward and backward rotation of the
mandible
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Chin cup appliance Also referred to as chin cap It is an extra oral orthopedic device
that covers the chin and is connected to a head gear
Used to restrict the forward and downward growth of the mandible
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Types of chin cup1) Occipital pull chin cup ndash
Derives anchorage from the occipital and parietal region
Used in class III malocclusions associated with mild to moderate mandibular prognathism
Also indicated in patients with slightly protrusive lower incisors as they invariably produce lingual tipping of the lower incisors
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
2) Vertical pull chin cup ndash
Indicated in patients with steep mandibular plane angle and excessive anterior facial height
These patients usually exhibit an anterior open bite
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Fabrication Chin cups are fabricated individually for
the patient or pre- fabricated commercially available chin cups are used
The fabrication of chin cup requires an impression to be taken of the chin area
The cast is poured and the chin cup is fabricated using self cure acrylic resins
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Force magnitude and duration of wear
At the time of appliance delivery a force of 150-300 grams per side is used
Over the next 2 months the force is gradually increased to 450-700 grams per side
The patient is asked to wear the appliance for 12-14 hours a day to achieve the desired results
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
indications
1) Patients with mild skeletal prognathism of the mandible
2) In case of increased facial height
3) Patients who has well aligned or protrusive but not retroclined mandibular incisors
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Conclusion To obtain desired dento-skeletal effect
with extra oral traction type of appliance amount of force location of centers of resistance of teeth maxilla amp craniofacial type must be considered
Different subjects may respond differently to same type of extra oral traction
Cervical combination and occipital facebow have similar A-P and vertical effects in growing patients
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Refrences Birte melsen and michel dalsta distal molar
movement AJODO 2003 123374-8 Leandro M Piva Helisio RLeite Maria
OrsquoReilly effects of cervical headgear and fixed appliances on space available for maxillary 2nd molar AJODO 2005 128()366-371
Haulabakis NB Sifakakis IB the effect of cervical headgear on patient with high or low mandibular plane angle and the myth of posterior mandibular rotation
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Serdar usumex metin orhan effect of cervical headgear wear on dynamic measurments of head position EJO 2005(27)437-442
RHASamuels N breziniak orthodontic facebows safety issues and current management JO2002(29) 101-107
Keith Godfrey extra oral retraction mechanics a review Austortho j 2004 2031-40
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Kloehn SJ Orthodontics- force or persuaion angle ortho 1953 2356-65
Arm strong MM controlling the magnitude duration and direction of extra oral force AJO 1971 59217-243
Jacobson A A key tounderstaing of extraoral forces AJO 197975361-386
Weislander L Long term effects of treatment with headgear-herbst appliance in early mixed dentition AJO 1993 104 319-329
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Hershey HG Houghton CW Burstone CJUnilateral facebows a theoretical and laboratory analysis AJO 198179229-249
Nanda R Biomechanics in clicnial orthodontics 1st edition philadelphia WB Saunders 1997130- 145
Turner PJ Extra oral traction Dent update 199118197-203
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
FirouzM Zernik J Nanda R denta and orthopedic effects of high pull headgear in treatment of class II div I malocclusion AJO 1992102197-205
Graber TM Extra oral force- facts and fallacies AJO 195541490-505
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG
Slide 120
Technique
Modification
Skeletal and Dental effects of FaceMask therapy
Chin cup appliance
Types of chin cup
Slide 126
Fabrication
Force magnitude and duration of wear
indications
Conclusion
Refrences
Slide 132
Slide 133
Slide 134
Slide 135
Patient compliance
Patient compliance An important aspect of using extra oral
traction is whether appliance is being worn as instructed
Patients compliance can be improved if both parents and clinician provide motivation
Extra oral appliances
Contents
Slide 3
Slide 4
Slide 5
ORTHODONTIC FORCE VS ORTHOPEDIC FORCE
Slide 7
Principles or Orthopedic appliances
Slide 9
Slide 10
Slide 11
Slide 12
Slide 13
Slide 14
Slide 15
Slide 16
Types of extra oral appliance
History
Slide 19
Slide 20
Slide 21
Slide 22
Slide 23
Slide 24
Slide 25
Slide 26
Classification of headgear
Appliance design
Slide 29
Slide 30
Outer bow (wisker bow)
Slide 32
Miscellaneous components
Slide 34
Cervical pull headgear
Slide 36
High pull head gear
Slide 38
Slide 39
Slide 40
Slide 41
Slide 42
Interlandi type headgear
Slide 44
Combination facebow
J-hook headgear
Slide 47
Slide 48
Slide 49
Slide 50
Slide 51
Assymetricalunilateral headgears
Slide 53
Slide 54
Slide 55
Biomechanics
Slide 57
Location of the centre of resistance
Slide 59
Slide 60
Greenspanrsquos study
Slide 62
Cervical headgear
Slide 64
Slide 65
Slide 66
High pull headgear
Slide 68
Slide 69
Slide 70
Straight pull Occipital headgear
Slide 73
Slide 74
Vertical pull headgear
Treatment effects
Anteroposterior dimension
Maxillary dentoalveolar position
Mandibular dentoalveolar position
Mandibular skeletal position
Vertical dimension
Mandibular plane angle and lower anteror facial hieght
Slide 83
Occlusal plane angle
Palatal plane angle
Transverse dimension
Slide 87
Slide 88
Slide 89
Slide 90
Slide 91
Slide 92
Headgear with activator
Slide 94
Head gear with herbst appliance
Clinical Implications
Anchorage control
Tooth movement
Slide 99
Orthopedic changes
Slide 101
Slide 102
Slide 103
Slide 104
Slide 105
Maxillary protraction with mandibular growth restriction
Slide 107
Slide 108
Indications
Sites of anchorage
Biomechanical considerations
Slide 112
Slide 113
Slide 114
Types
Slide 116
Slide 117
Slide 118
Influence of rapid maxillary expansion used with protraction HG