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class III malocclusion

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Content: 1.introduction 2.etiology 3.skeletal and dental factors

4.occlusal feature

5.classification

6.treatment 7.surgical treatment

8. future innovative techniques for class III treatment

9.Conclusion10.Reference

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Introduction

The Skeletal

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inter-occlusal relationship with the teeth in the retruded contactposition.The british standards definition of class III incisor relationshipincludes those malocclusions where the lower incisor edge occludesanterior to the cingulum plateau of the upper incisors.Anteroposterior 'sagittal discrepancy in here is less than normal or

possesses a ve vertical relationship, if dentally then the O.J. =1mmor less up to ve, and if a skeletal classIII discrepancy then the ANBangle =1degree and less depend upon severity.

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Etiology :

1.early closure of the nasomaxillary complexsutures in certain syndromes.

2.hereditary ,small size maxilla and big size

mandible.3.collapsed maxilla for cleft lip and palate

patients.

4.mouth breathing individuals.

5.environmental,collapse of maxilla occur when

extraction of multiple permanent teeth occur

earl in life.

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Skeletal pattern:

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Mandibular, maxillary ,and cranial base factors make acombined :contribution to the underlying classIII skeletalthrough

1.Usually Class III associated with along mandible

2.forward placement of the glenoid fossa positioning themandible more anteriorly

3.short and/or retrognathic maxilla

4.short anterior cranial base or a combination of these.

the vertical relationship of the skeletal bases varies fromincreased to average or reduced and is generally reflectedin the depth of overbite, which may alter depending onthe pattern of facial growth. Where this is vertical rather

than horizontal ,an anterior open bite is likely.Commonly ,a transverse discrepancy exists in the dentalbase relationship because of the narrow maxillary andwider mandibular bases ,although this is often worsened

by the classIII skeletal pattern.

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SOFT TISSUE:

The soft tissue surrounding play a very minor effect

in the etiology of class III malocclusion whencompared with their effect in class II malocclusion.

Where the lips competent, the lips and tongue induse

retroclination of the lower incisors and prolination ofthe upper incisors (dentoalveolar compensation).

Where the lower anterior facial height is increased

the lower lips are frequently incompetent, with anadaptive tongue thrust on swallowing which may

procline the lower incisors.

In sagittal direction except in sever skeletal III cases

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DENTAL FACTORS:

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Crowding is more common and more sever inthe upper than in the lower arch ,oftenresulting from the difference in length and

width of the arches. The upper frequently isshort and narrow compared with a longer andwider lower arch.

OCCLUSAL FEATURE:

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1.The lower incisor edge lie anterior to thecingulum plateau of the upper incisors, the overjet isreduced or reversed' (british standards institute

classification) 2.The overbite may be increased ,average ,or

reduced. Where the vertical facial proportions areincreased ,there is often an anterior open bite.

3.Frequently, the upper incisors are proclined andthe lower incisors retroclined, compensating for theunderlying classIII skeletal pattern.

4.Upper arch crowding is common, often becauseof a short and narrow dental base, while the lowerarch is more commonly aligned or spaced.

5.Crossbite of the labial and/or buccal segments arecommon resultin from the underl in classIII

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THE MAIN VARIANTS IN VE SAGITTAL

OR CL III are:

1. Degree of skeletal discrepancy.2. Degree of improper anterior teeth position and

inclinations that lead to a ve o.j.

3. If there are other discrepancies rather than sagittal

in the other two directions or within the arch.

.

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Many classifications of severity of class III had been reviewed, theaccepted one as follow:-

1.mild CL III 'dental' :

O.J. is purely dental due to different axial inclination of U/Lanterior teeth or one of them ,O.J.=(0,-1,-2 mm)

2. moderate CLIII 'dento-skeletal' :

In which the cause of the reverse O.J. may be attributed partly tojaws and the other part to teeth together O.J.=

(-1,-2,-3 mm)

3.sever CL III 'SKELETAL' :

In which the cause of the reverse O.J. is a result of improperpositions i.e. the maxilla is retruded and the mandible is protruded

'one of them or both '. in this situation orthognathic surgery is thesolution of this discrepancy with the help of the orthodontist.

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TREATMENT OF CL III MALOCCLUSION:-

Treatment Planning:

Consider the degree of 1.anteroposterior and vertical

skeletal discrepancy,

2. the potential direction and extent of future facial

growth, 3.incisor inclinations,the amount of overbite, 4.the ability to achieve edgeto-edge incisor relationship, 5.and the degree of upper and lower arch crowding.

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According to the classification the treatment of type 3 bysurgery while type 1&2 the postural can be treatedorthodontically alone after removing or treating the cause

by:-

1.proclination of upper anterior teeth

2.retroclination of lower anterior teeth

The amount of both movement may be limited oraccepted or one of them .

such movement can be performed by removableappliance via:

R Z i f li i

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a. R.Z.springs for proclination or screws . b.Hawley arch for retroclination &also can be

done by fixed appliance

3 th f l iii l ti

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3.the use of class iii elastics

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That are attached to U/L fixed appliances

extending from the upper molars to lower canines,

that when the patient open and close the mouth

there will be a stretching thus a reciprocal teeth

movement will occur by sliding the upper arch

anteriorly and the lower arch posteriorly.

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4.Treatment by growth modification:

Myofunctional appliances:-

REVERSE-PULL

HEADGEAR

'trade mark' Chin Cap

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Long time ago the age of 8 years was regarded as the

time when an individual meet the orthodontist for the

first time to evaluate his/her condition. Nowadays the

age is 4 years where the orthodontist can predict thatthe patient will develop a malocclusion in the future

and especially CLIII susceptible individuals.

The 'trade mark' Chin Cap is preventive myofunctionalappliance that is used to prevent ,modify or break the

unwanted downward and forward growth of the

mandible by directing the force by the chin cap across

the growth center of the mandible "condyle"back ward

and upward bilaterally. the time elapsed to wear the

chin cap is 12-16 hours per day and should last until

adulthood or late adolescent by the age of 15-16 years.

REVERSE PULL h d Al k f k i

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REVERSE-PULL headgear Also known as a face-mask, isused to apply an anteriorly directed force via elastics, on themaxillary teeth and maxilla. Although some have claimedthat this appliance can change the position of maxilla, averycooperative patient is necessary in view of the prolongeddaily wear equired, often over several years. Nevertheless,this technique is occasionally useful in the management ofclass iii malocclusion ,particularly those associated with acleft lip and palate anomaly, and also in cases of hypodontiawhere forward movement of the buccal starting point to usethe chin cap can be done as soon as the lower permanentincisors erupt ,and even we can use it before puberty to

assist treatment of cl iii.segment teeth to close space isdesirable.

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is one of the series of frankle appliance that is used tocorrect cl iii as soon as possible if the case demands the

use of such appliance. Again it can be used as early as 7

years if the patient can tolerate its use.

In treatment of cl iii the correction of the OB &OJ &the

canine relationship beside the correction of the crowding

&x-bite if present is more important than the correction

of the molar relationship. if an additional malocclusion

feature is associated (compartment A) then the line of

treatment is modified to overcome and treat the casesimultaneously, i.e. post. x-bite ,open bite others.

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5."postural class III" :

Pre treatment

Si th b d b t th l CL I l ti d th

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Since the borders between the normal CL I relation and the

abnormal CL III cases and in such cases a cl I at the

primary dentition and when the eruption of permanent

dentition take place especially the anterior teeth, theyappear edge to edge and then a translocated to a reverse

O.J. relationship, such postural relationship (centric

occlusion not coincident with the centric relation) i.e.

when the dentist guide the mandible to the centric

occlusion only a premature contact occur in the incisors

leaving the posterior teeth with no occlusion and when a

maximum posterior occlusion is needed to grind the foodthe mandible is shifted anteriorly and a reverse O.J. which

is the cross bite.

The treatment in this case is simple if done as earl as

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The treatment in this case is simple if done as early as

possible when discovered and give an excellent results by

correcting the reverse O.J. by using a fixed or removable

appliance . In patients presenting with a deep overbite, amandibular Hawley appliance with an anterior labial bow

can be used to prevent forward movement of the lower

incisors during bite jumping. In most cases crossbite

correction is maintained by the overbite, and no retention

appliance is necessary.

Post treatment

Severe Class III skeletal pattern:

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Severe Class III skeletal pattern:

Surgical treatment:

the prensece of a reduced overbite or an anterior open bite preclude

orthodontics alone, and surgery is necessary to correct the underlyingskeletal discrepancy. That surgery is almost required if the value for

the ANB angle is below -4 and the inclination of the upper incisors to

the mandibular plane is less than 83*. The cephlometric finding

should be considered and the patient's facial appearance. With thosepatients who have sever skeletal pattern with lack of overbite, a

surgical approach should be explored before any permanent

extractions are carried out, and preferably before any appliance

treatment. The reason for this is that management of class iii

malocclusions by orthodontics alone involves dento-alveolar

compensation for the underlying skeletal pattern.Any dento-alveolar

compensation must first be removed or reduced.

For example if lower premolars are extracted in an attempt to retract

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For example, if lower premolars are extracted in an attempt to retract

the lower labial segment but this fails and a surgical approach is

subsequently necessary, the presurgical orthodontic phase will

probably involve proclination of the incisors to a more average

inclination with reopening of the extraction spaces. This is a

frustrating experience for both patient and operator.

The prevalence of class III malocclusion in our community is less

when compared with the class II malocclusion ,it's prevalence from

3% to 7% as a maximum occurrence.

FUTURE INNOVATIVE TECHNIQUES FOR

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FUTURE INNOVATIVE TECHNIQUES FOR

CLASS III TREATMENT 1.Distraction Osteogenesis to Advance the Maxilla:

Distraction osteogenesis has recently been used to simulate a Le Fort I

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Distraction osteogenesis has recently been used to simulate a Le Fort I

maxillary advancement and anterior segmental repositioning. An

incomplete osteotomy placed above the canine and molar roots was

performed through a vestibular incision. Pterygomaxillary disjunction

and dissection of the nasal floor and septum were not performed.

Distraction forces were placed on the maxilla by a reverse-pull

headgear and an intraoral orthopedic appliance to advance the maxilla

8 to 12 mm. An incomplete osteotomy placed above the canine and

molar roots was performed through a vestibular incision.Pterygomaxillary disjunction and dissection of the nasal floor and

septum were not performed. Distraction forces were placed on the

maxilla by a reverse-pull headgear and an intraoral orthopedic

appliance to advance the maxilla 8 to 12 mm.

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2.Dental Onplants to Provide Absolute Anchorage for Maxillary

Protraction:

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One of the limitations in

maxillary protraction withtooth-borne anchorage

devices such as expansion

appliances and palatalarches is the loss of dental

anchorage (i e C l i

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Conclusion: At the end of this period in all cases the

correction of anterior crossbite and the

elimination of the mandibular displacement

were obtained, The goals of this approachare as follows:

1.prevents unfavourable growth especially

mandibular protrusion; irreversible, soft

tissue 2.prevents habits such as

bruxism;

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Thankyou.

thankyou.