Aob correct by le fort i or bsso

Oral Maxillofacial Surg Clin N Am 19 (2007) 321–338

Anterior Open Bite Correction by Le Fort Ior Bilateral Sagittal Split Osteotomy

Johan P. Reyneke, BChD, MChD, FCMFOS (SA), PhDa,b,*,Carlo Ferretti, BDS, MDent (MFOS), FCD (SA) MFOSa,c

aDepartment of Maxillofacial and Oral Surgery, Faculty of Health Sciences,

University of the Witwatersrand, Johannesburg, South AfricabDepartment of Oral and Maxillofacial Surgery, Faculty of Dentistry,

University of Oklahoma, Oklahoma City, OK, USAcDepartment of Maxillofacial and Oral Surgery, Chris Hani Baragwanath Hospital,

Faculty of Health Sciences,

University of the Witwatersrand, Johannesburg, South Africa

Some of the most challenging dentofacial de-formities facing surgeons and orthodontists areanterior open bite malocclusions. Determining thecause of an anterior open bite and formulating

a diagnosis are complicated by the role ofneuromuscular and genetic influences. Long-termskeletal and dental stability are a concern because

of the influence that the neuromusculature has onthe repositioned jaws and stability of teeth aftervertical orthodontic mechanics required for clos-

ing open bites.

Etiology

Mechanistic insights on the development of theanterior open bite malocclusion remain subject todebate and discussion. Patently, two philosophies

may concur with research findings: the morpho-genetic theory and the adaptive theory. Theanterior open bite may be the result of aberrant

genetic control of morphology via growth pat-terns, or a malformation secondary to functionalaberrations of the naso-oropharyngeal apparatus.

It has proven difficult to separate these two

* Corresponding author. Centre for Orthognathic

Surgery and Implantology, Sunninghill Hospital, PO

BOX 5386, Rivonia, South Africa.

E-mail address: [email protected] (J.P. Reyneke).

1042-3699/07/$ - see front matter � 2007 Elsevier Inc. All

doi:10.1016/j.coms.2007.04.004

causative mechanisms, and the question remainsincompletely answered.

Nonnutritive sucking is a normal developmen-tal phenomenon whose frequency decreases with

age. Persistence of the habit beyond the age of 6years is strongly associated with open bite maloc-clusion [1]. Complicating the issue is the fact that

there is a wide racial variation in the incidence ofanterior open bite, which suggests a modulating ef-fect of genetic control of skeletal proportions [2,3].

Nasopharyngeal and oropharyngeal obstruction asa result of one of several possible conditions, suchas allergic rhinitis, enlarged adenoids, and enlarged

tonsils, has been associated with development ofanterior open bite deformity [4].

It is proposed that obstruction to normal nasalbreathing triggers an adaptive neuromuscular

response that results in open rotation of themandible, inferior and anterior repositioning ofthe tongue, and extended head posture giving rise

to the classical ‘‘adenoidal facies.’’ There areseveral implications of these functional adapta-tions to nasal breathing. First, a change in the

direction of mandibular growth from horizontalto vertical results in increased lower facial height.Second, inferior and anterior repositioning of the

tongue has several dental effects, includingnarrowing of the maxillary dental arch causedby the unopposed action of the buccinator muscle,retroclination of the upper incisors caused by

the unopposed actions of orbicularis oris, and

rights reserved.

oralmaxsurgery.theclinics.com

mailto:[email protected]

322 REYNEKE & FERRETTI

proclination of the lower incisors caused byincreased tongue pressure. The case for thismechanism has been strengthened by the finding

that early removal of the obstruction and returnto nasal breathing often results in normalizationof anterior height. Finally, chronic mouth breath-ing can cause alterations in head posture, most

commonly extension or upward rotation of thehead, in an attempt to improve oropharyngealpatency. This altered posture has been associated

with several disturbances in craniofacial morphol-ogy, including increased lower facial height,mandibular and maxillary retrognathism, and

steep mandibular plane.Increased vertical development of the maxilla

also has been associated with several muscleweakness syndromes. Weakness of the mandibu-

lar elevators and decreased biting force allow theposterior teeth to overerupt and the mandible torotate downward. It has been reported that the

biting forces of patients with long faces are belownormal, although the bite force of preadolescentpatients with long face characteristics is normal

[5,6]. The role of decreased bite force as an etio-logic factor in the development of vertical maxil-lary excess and anterior open bite is not clear,

however.In the past, tongue thrust or abnormal tongue

activity during speech has been blamed for thedevelopment of anterior open bite malocclusion

and poor stability after treatment. Various at-tempts to change patients’ swallowing patterns,such as speech therapy and removable appliance

with a crib, have been used to control anterioropen bite problems. Contemporary research hasshown, however, that tongue thrust swallow is

a physiologic adaptation to an anterior open biterather than the cause of it. An abnormally largetongue or true macroglossia should first bedifferentiated from pseudomacroglossia and only

then considered as an etiologic factor in thedevelopment of an anterior open bite. A largetongue also may be the cause of poor stability

after treatment [7].It seems that an anterior open bite is pre-

dominantly the result of alterations in mandibular

growth patterns, and more attention is requiredfor treatment philosophies that address this fact.

Diagnosis

As with the diagnosis of all malocclusion, it isimportant to identify the cause of the anterior

open bite. Because vertical problems (in particularin patients with anterior open bite) can result fromhabits, environmental influences, or vertical skel-

etal growth problems, the diagnosis has twoimportant components: the specific anatomiclocation of the discrepancy (eg, maxilla, mandible,or both) and identification of a cause. In young

growing individuals, the major cause of anterioropen bite is sucking habits and environmentalinfluences. The open bite as a result of thumb

sucking is usually limited to the anterior region,with a narrow palate, often posterior cross bites,and relatively normal facial proportions. The

most important step in the treatment is to stopthe habit. For this purpose a removable appliancewith a crib is used. The sucking habit stopsimmediately in approximately 50% of patients

and the open bite starts to close rapidly. In theremaining children the thumb sucking may persistfor a few weeks; however, the device is usually

effective in 85% to 90% of cases [1]. At this stage,orthodontic correction of the cross bites solves thetransverse and anterior open bites. The long-term

prognosis depends on the growth pattern, how-ever, and a poor response to treatment suggestspersistent excessive vertical growth. These patients

most probably develop vertical maxillary excessand an anterior open bite malocclusion.

Not all children who are thumb suckers de-velop anterior open bites. In children with chronic

mouth breathing, one, or all, of three neuromus-cular responses must be present for an anterioropen bite malocclusion and altered skeletal re-

sponse to develop: (1) altered mandibular posture,(2) altered tongue posture, (3) extended headposture [4]. Several studies have shown that an

obstructed upper airwaydassociated with alteredmandibular posturedis related to increased lowerfacial height [8,9]. Removal of the cause of the na-sopharyngeal obstruction (eg, enlarged adenoids

or tonsils, allergic rhinitis) has been reported todecrease the open bite [4]. Upper airway obstruc-tion may be one factor in the multifactorial etio-

logic complex that influences the dentition andmorphogenetic facial pattern.

In young individuals in whom vertical growth

persists and in patients who have reached adoles-cence, environmental causes for anterior open bitebecome less important than skeletal factors. Skel-

etal anterior open bite malocclusion in adults isbasically a vertical dentofacial problem caused byexcessive vertical development of the maxilla,shortening of themandibular ramus, or a combina-

tion of both. It is important to distinguish between

323ANTERIOR OPEN BITE CORRECTION

Fig. 1. An anterior open bite (A) in an 8-year-old patientwas treated by orthodontic expansion of themaxillary dental arch

combinedwith habit control (thumb sucking) (B). The arrow indicates the ‘‘gate’’ incorporated into a removable appliance.

A stable posttreatment result was achieved (C). (Courtesy of T. McCollum, BDS, MDent, Johannesburg, South Africa.)

the two skeletal deformities because it ultimatelydetermines the surgical treatment plan.

Treatment of growing individuals

Anterior open bites in children with mixeddentition and good facial proportions are usuallycaused by prolonged thumb sucking (beyond the

age of 6 years) or other environmental influences,and the most important corrective measure inthese patients is cessation of the habit. Posterior

cross bites are usually the result of narrowing ofthe maxilla. Removable and fixed appliances canbe effective in the correction. Maxillary dental

expansion not only corrects the cross bites butalso assists in closing the anterior open bite andshould be combined with habit control (Fig. 1).By the time adolescence is reached, environmental

causes become less important. Skeletal factorsshould be considered after poor response to habitcontrol and maxillary expansion [10].

Treatment of nongrowing individuals

Orthodontic correction of anterior open bite

The treatment of patients with anterior openbite by means of orthodontic treatment aloneusually focuses on three areas: (1) extrusion of

upper and lower incisor teeth, (2) intrusion ofmolar teeth, and (3) expansion of the maxillarydental arch. This orthodontic treatment requires

almost exclusively the use of vertical mechanics.Extrusion of incisor teeth can be accomplished inthree ways: (1) the use of anterior elastics, (2)

using a continuous arch wire from molar to molarto level an excessive occlusal curve in the maxil-lary arch, and (3) leveling a reverse curve of Spee

in the lower arch in the same manner. Themechanics to intrude the molars include intrusionof molars with miniplate anchorage [11], high-pull

headgear and class III elastics [12], titanium screwanchorage [13], a rapid molar intruder appliance

[14], reverse headgear combined with class III

Box 1. Clinical, dental, andcephalometric findings of patientswith anterior open bite deformity

Aesthetic featuresLower third of the face almost always

elongatedExcessive incisor exposure under the

upper lipIncreased interlabial gapGummy smileObtuse nasolabial angleRetrusive chin

Dental characteristicsOpen bites may be associated with all

types of malocclusion; however,relative or absolute mandibulardeficiency and class II malocclusionare most common

Tendency for the maxillary arch to beV-shaped and the mandibular arch tobe U-shaped

Posterior cross bitesFlat or reverse mandibular occlusal plane

curveStepped maxillary occlusal plane

Cephalometric featuresIncreased anterior facial heightSteep mandibular and occlusal plane

angleNormal mandibular ramus heightSaddle cranial baseIncreased distance from tooth apices to

the nasal floorPalatal plane is tipped up anteriorly and

down posteriorly


Fig. 2. This 17-year-old patient developed an anterior open bite as a result of excessive vertical growth of her maxilla.

The mandible rotated clockwise, which resulted in a class II anterior open bite malocclusion (A–F). The maxillary dental

arch was aligned in two segments (11 to 17 and 21 to 27) (G–L). The open bite was surgically corrected by superior

repositioning of the maxilla (more in the posterior area than anterior) and expanded, which allowed the mandible to

autorotate (O). A balanced aesthetic result and functional occlusion were achieved (M–R).

and anterior box elastics [15], zygomatic anchor-age [16], and bite blocks with repelling magnets[17]. Expansion of the maxillary posterior teeth

in adult individuals with skeletal transversedeficiency usually results in dental tipping andquestionable stability [18,19].

Most of the reports in the literature regardingorthodontic correction of skeletal anterior openbite are case reports that discuss specific ortho-

dontic techniques or introduce new orthodonticmechanics. There is, however, a paucity of studiesregarding results after orthodontic correction of


Fig. 2 (continued)

anterior open bite malocclusions to draw anyevidence-based conclusions [20–22]. Few studies

have reported on the pretreatment aesthetic con-siderations and facial aesthetic outcomes. Regard-less of the specific mechanism used to achieve thetooth movements, stability is unpredictable and in

many cases results in compromised aesthetics[23,24]. In cases in which the anterior open biteis associated with increased incisor angulation

(as may be found in cases with bimaxillaryprotrusion), correction of the incisor angulationby tipping the incisors has a relative extrusion

effect, thus closing the bite.

Combined orthodontic and surgical treatment

Anterior open bite secondary to vertical maxillary

excess: Le Fort I maxillary osteotomy with orwithout mandibular surgery

The common but variable clinical, dental, and

cephalometric findings of patients with skeletalanterior open bite deformity as a result of verticalmaxillary excess are as shown in Box 1 (Fig. 2):

Presurgical orthodontic treatmentPresurgical orthodontic mechanics should not

be directed toward correcting vertical, transverse,or anteroposterior skeletal problems. Orthodontictooth movements for the correction of these

problems have questionable long-term stabilityand may build relapse into the surgical result. The

basic goal of presurgical orthodontic treatmentshould be to align the maxillary teeth (either insegments or in one piece) and avoid any mechanicsthat are intended to close the bite. Segmental

surgery is indicated when the maxillary dentalarch has a tendency to natural segments or to levelthe occlusal curves surgically. This does not mean

that individual teethwithin a segment should not beleveled; intrusion of the incisors or maintainingtheir pretreatment height is recommended. Open-

ing the bite before surgery improves stabilitybecause relapse of incisor intrusion serves to furtherclose the bite after surgery. Orthodontic alignmentof the maxilla in segments can be done with or

without extractions. The need for extractions inthese cases is dictated by the amount of crowdingand the dental movements necessary to place the

upper and lower incisors in their desired angulationand in the central troughof bone.Keep inmind thatthe angulation of the incisor and posterior teeth can

be altered with segmental surgery. In cases in whichsegmental surgery is contemplated, care should betaken to coordinate the arch form of the maxillary

segments with the mandibular arch and deviate theroots of the teeth adjacent to the intended in-terdental osteotomy sites.



Although the mandible may require surgicaladvancement or setback, the lower dental archserves as the ‘‘template’’ and ultimately dictatesthe symmetry and form of the upper arch. The

presurgical orthodontic treatment goals are toplace the lower dentition symmetrically in theideal anteroposterior, vertical, and transverse

positions in relation to its supporting bone. Inindividuals with a severe reverse curve of Spee inthe lower arch, consideration should be given to

surgically leveling the mandibular arch by meansof segmental mandibular surgery.

Orthodontic mechanics expressly intended to

close the bite should be avoided during thepresurgical orthodontic phase. Bite blocks withrepelling magnets, high-pull headgear, miniplateanchorage for molar intrusion, vertical elastics,

molar expansion beyond its alveolar bone base, orany other device used to close the bite areinadvisable. Previous attempts to close a skeletal

anterior open bite orthodontically without con-sidering surgical correction will leave the clinicianwith a dilemma. After orthodontic attempts to

close the bite, pretreatment orthodontic recordsmust be compared with current records to evalu-ate the potential for dental relapse. It is recom-

mended to discontinue all vertical mechanics andallow vertical relapse by placing light sectionalarch wires to maintain alignment and rotations.Once no further vertical opening of the bite

occurs, the patient can be re-evaluated for appro-priate surgery and orthodontics.

SurgeryThe anterior open bite in this group of patients

is caused by excessive vertical growth of themaxilla. The vertical deformity often occurs inconjunction with either a primary or secondary

sagittal deformity. During treatment planningthree factors should be considered: (1) the amountof superior repositioning of the maxilla, (2) the

position of the mandible after autorotation, and

(3) the need for surgical correction of a transversediscrepancy.

The amount of superior repositioning of the max-

illa. The amount of superior repositioning of theanterior and posterior maxilla is influenced by twoaspects: (1) The planned ideal maxillary incisor/upper lip relationship determines the amount of

vertical and anteroposterior repositioning of theanterior maxilla. In most cases the incisor teethrequire superior repositioning. In some cases,

however, the incisor height may need to bemaintained, whereas in other cases the anteriormaxilla may have to be inferiorly repositioned.

The final anteroposterior and vertical positions ofthe maxillary incisor are the key to treatmentplanning [25,26]. (2) The final occlusal plane is

determined by the mandibular occlusal plane afterautorotation of the mandible. The amount ofsuperior repositioning of the posterior maxilla isdetermined by the height of the mandibular

posterior teeth after autorotation.

The position of the mandible after autorotation.The anteroposterior position of the lower incisor

after autorotation determines whether mandibularsurgery is indicated. Individuals with a class Imolar relation, combined with vertical maxillary

excess and an anterior open bite malocclusion,end with a class III dental relationship aftermaxillary superior repositioning. Based on the

aesthetic requirements of the case, the clinicianmust decide whether the class III dental relation-ship should be corrected by advancement of themaxilla (Fig. 3) or mandibular setback (Fig. 4).

The mandible of an individual with verticalmaxillary excess and a class II occlusion rotatesto a class I relation after superior repositioning

of the maxilla and may not require mandibularsurgery. Patients with class III anterior open biteand vertical maxillary excess end with a class III

occlusion of increased severity after verticalcorrection of the maxilla and anterior rotationof the mandible. These cases most probably need

a mandibular setback procedure in conjunction

Fig. 3. The typical clinical signs of vertical maxillary excess (ie, increased lower facial height, the appearance of

mandibular deficiency, and convex profile caused by the backward rotation of the mandible). A gummy smile and an

increased interlabial gap are well demonstrated in this 19-year-old patient (A–D). He had a class I open bite malocclusion

and a tendency to bilateral posterior cross bites (E). The upper dental arch was orthodontically aligned in one segment

and the lower arch leveled (F). The surgical treatment plan consisted of a three-piece Le Fort I maxillary osteotomy with

superior repositioning and expansion of the maxilla. The mandible autorotated into a class III dental relation. The facial

aesthetics required maxillary advancement rather than mandibular setback. For optimization of facial aesthetics, the

chin was advanced by means of a genioplasty (G,H). The posttreatment results (I–M).

:


Fig. 4. This 22-year-old male patient presented with an increased lower facial height, mandibular prognathism and asym-

metry to the left, and a class III anterior openbitemalocclusion (A–C). The preoperative orthodontic treatment consisted of

the aligning the maxillary arch in three segments (the anterior segment, including the four incisor teeth), and leveling the

lower dental arch (D–F). The treatment plan consisted of superior repositioning and expanding the posterior maxilla by

means of a three-piece Le Fort I osteotomy, which allowed the mandible to autorotate and close the open bite. The class

III dental and skeletal relation, however, worsened after autorotation of the mandible, which necessitated mandibular set-

back and correction of the mandibular asymmetry at the same time (G, H). The posttreatment results (I–N).

with maxillary advancement (see Fig. 4). Thisdecision is based on the aesthetic requirementsof each case. Individuals who have vertical maxil-lary excess and severe class II malocclusion and

anterior open bites end with a class II occlusal re-lationship after maxillary superior repositioning.To establish a class I occlusion, these cases often

require additional mandibular advancement pro-cedures (Fig. 5).

Poor midface esthetics are usually the conse-quence of maxillary setback procedures (>3 mm).A combination of maxillary superior reposition-ing and setback will compromise the esthetics even

more and should be avoided. The mandibleshould rather be advanced in these cases, andthe maxilla superiorly repositioned and preferably

slightly advanced. The slight advancement (2–3mm) has the added technical advantage that the


Fig. 4 (continued)

posterior maxilla is moved away from thepterygoid plates, which avoids difficulty in re-moving bone posteriorly to allow for adequate

superior repositioning of the posterior maxilla.Because of the disproportionate vertical excessof the posterior maxilla in open bite deformities,

it often requires more bone removal in this areathan in correction of non–open bite deformitieswith vertical maxillary excess. In all of these

treatment scenarios the chin contour and posi-tion should be evaluated to enhance the aes-thetic outcome. When considering a genioplastyprocedure, two important aspects should be kept

in mind: (1) genioplasty is not a substitute formandibular surgery and (2) chin shape orcontour is more important than chin position

(anteroposterior position of pogonion).

The need for surgical correction of a transversediscrepancy. An individual with an open bite

malocclusion and skeletal vertical maxillary excessoften has a transverse skeletal deficiency of themaxillary arch. These cases require surgical expan-sion of the maxilla by segmental surgery. Surgical

expansion of the maxilla has been shown to be oneof the most unstable orthognathic procedures,however [27]. Transverse relapse is one of the

most common postsurgical complications and in-evitably leads to recurrence of the anterior open

bite. The problem often stems from poor preopera-tive diagnosis, inappropriate presurgical orthodon-tics, poor surgical management, and poor

postsurgical orthodontic control [28]. Initially theclinician should determine whether the discrepancyis skeletal or dental in nature and whether it is rel-

ative or absolute. Only when the dental casts areheld in their correct sagittal relationship with thecanines in a class I occlusion can an absolute cross

bite be revealed. When the cross bite is obviouslyskeletal in nature, compensatory dental expansion,headgear, arch wires or through-the-bite elasticsshould be avoided. These dental changes have

a high potential for relapse that may only manifestlong after treatment [29].

Presurgical orthodontic tipping of molar teeth

that leaves the lingual cusps hanging below theocclusal plane has additional surgical problems.Hanging palatal cusps of the molars increase the

amount of surgical expansion of the palate that isrequired. Surgical palatal expansion in these caseswould involve expansion of the bony base and anelement of uprighting of the molar teeth. The

increased amount of expansion leads to increasedpotential for relapse (Fig. 6).

Transverse stability can be enhanced by

placing a bone graft in the palatal defect.Stabilization of the bone graft can be facilitatedby performing the palatal osteotomy in the


Fig. 5. A 16-year-old female patient with a class II anterior open bite malocclusion (A–C). Her maxilla was vertically

excessive and mandible anteroposteriorly deficient. Both dental arches were orthodontically leveled, aligned, and coor-

dinated before surgery (D). After the superior repositioning of her maxilla, the bite was closed and the mandible rotated

into a class II occlusion. Her mandible was advanced by means of a bilateral sagittal split osteotomy and her chin

augmented by means of a sliding genioplasty (E, F). The posttreatment results (G–J).

mid-palate, where the bone is thickest. Thedisadvantage is that the mucosa in this area of

the palate is at its thinnest. A tear in the palatalmucosa exposes the graft and eventually leads to

loss of the graft. Performing bilateral osteoto-mies in the palate facilitates larger expansion;

however, grafting these areas where the bone isthin is more difficult.


Fig. 6. With the maxillary posterior teeth in good angulation, a 5-mm expansion of the upper dental arch creates a 5-mm

bony defect in the palate (A, B). When the posterior teeth are orthodontically expanded, however, the molar teeth are

tipped buccally and the palatal cusps tend to hang. The expansion of the upper arch also needs to include a rotational

movement to ‘‘tuck’’ the buccal cusps in. A 5-mm dental expansion leads to a 10.5-mm bony defect (C, D).

The use of a splint during surgery andmaintaining the splint in position for at least 6

weeks after surgery allow stabilization duringbone healing and may enhance skeletal stability.Obtaining immediate postsurgical orthodontic

control by placing a palatal bar or a strong archwire or both to support the palatal expansionfurther enhances stability of the result. In patients

who have macroglossia, reduction of the tongueat the time of orthognathic surgery should beconsidered. An abnormally large tongue does notadjust to the decreased oral volume after surgical

correction and plays an important role in relapse.A normal-sized tongue with forward posturingdoes adjust to the smaller volume after surgery,

however. Pretreatment tongue thrust swallowingdisappears after correction of the anterior openbite because the physiologic necessity for tongue

thrust has been eliminated.

Open bite secondary to short mandibular ramus

with a normal condyle: mandibular surgeryThe clinical features of individuals with

anterior open bites as a result of deficiency of

the mandibular ramus height differ from patientswith vertical maxillary excess. Although variable,the clinical features are as shown in Box 2 (Fig. 7).

Preoperative orthodontic treatmentIn general, avoidance of presurgical bite-closing

mechanics also applies in these cases. A transversediscrepancy between the upper and lower arch mayexist. The absolute or true transverse discrepancy

can be measured by holding the models in thedesired class I relation. The potential cross bitesshould be corrected orthodontically if the discrep-

ancy falls within the range of stable orthodonticmovement. When an absolute cross bite existsbecause of a transverse maxillary deficiency thatis not the result of dental tipping, three surgical

options should be considered: (1) surgically assistedexpansion of the maxillary dental arch [30], (2) nar-rowing of the mandibular arch by an osteotomy

through the symphysis [31,32], and (3) two-jaw sur-gery with surgical expansion of the maxilla bymeans of segmental surgery [33].

SurgeryIndividuals who have anterior open bite as

a result of short mandibular rami do not have the

typical facial, skeletal, and occlusal features asso-ciated with patients with vertical maxillary excessand open bite. Aesthetic and functional correction

in these cases demands a different surgicalapproach, and consideration should be given tocorrecting this type of dentofacial deformity by


means of mandibular surgery. Surgical closure ofan anterior open bite by mandibular surgery in-volves counterclockwise rotation of the mandibleat the posterior teeth. Historically this surgical

movement of the mandible has been considered tobe unstable [27]. Reports in the literature identifythree main factors that may influence the stability

after orthognathic surgical procedures: (1) stretch-ing of soft tissue, (2) neuromuscular adaptation,and (3) alteration of the muscle orientation [27].

These factors are particularly important when clos-ing an open bite by counterclockwise rotation ofthe mandible.

Stretching of soft tissue. If the mandible is rotatedcounterclockwise by means of a bilateral sagittal

Box 2. Features of anterior open bitecaused by deficiency in mandibularramus height

Aesthetic featuresNormal incisor upper lip relationsNormal paranasal configurations and

alar base widthsSufficient upper lip support and nasal tip

projectionsSlightly increased anterior lower facial

heightConvex profile and retrusive chin

Dental characteristicsClass II occlusion is usually present (the

dental relation should be seen in thecontext of the horizontal change afterback and downward rotation of themandible as a result of the shortmandibular ramus)

Maxillary and mandibular dental archesexhibit normal occlusal curvesalthough the occlusal planes deviate

Transverse dimensions of the dentalarches are usually coordinated

Cephalometric featuresNo posterior vertical maxillary excessShort mandibular ramus heights, which

may be associated with mandibularanteroposterior excess or deficiency

Mandible of an individual with class IIIocclusal relation appears excessivewith a concave profile; individuals withclass II occlusions exhibit convexprofiles and retrusive chins

ramus osteotomy, two muscle groups arestretched: the suprahyoid muscles and the medialpterygoid and masseter muscle. The suprahyoid

musculature is lengthened when the symphysis ofthe mandible is rotated superiorly and is furtherstretched after mandibular advancement and gen-ioplasty. Although suprahyoid myotomies have

been used successfully in animal studies to de-crease postsurgical relapse [34], human studieshave not supported these results [35]. Epker advo-

cated clinical evaluation of the patient and carefulexamination of the cephalometric prediction todetermine the possible need for suprahyoid myot-

omies [36]. Measurement of the potential length-ening of the suprahyoid muscles is made fromthe surgical treatment prediction tracing. If thesuprahyoid muscles will lengthen more than

30%, a suprahyoid myotomy is indicated [37].The amount of suprahyoid muscle stretch wouldbe influenced directly by the amount of mandibu-

lar rotation required to close the open bite. Theauthors believe, however, that the role of supra-hyoid muscle stretch in long-term stability needs

further research.When the sagittal split ramus osteotomy is

performed (as described by Trauner and Obwe-

geser [38] and modified by Dal Pont [39]) and thedistal segment is rotated counterclockwise, theposterior mandibular height is increased (Fig. 8).Downward rotation of the distal segment at the

mandibular angle and lengthening of the ramusstretches the pterygomandibular sling and soft tis-sue envelope. Postoperative muscular force leads

to poor proximal segment control and causes skel-etal relapse [40]. Splitting the mandibular ramusalong the lower border followed by counterclock-

wise rotation also stretches the medial pterygoidmuscle and the stylomandibular ligament on themedial aspect of the mandibular ramus (Fig. 9).

When the sagittal split of the mandibular

ramus is performed according to the modifiedtechnique suggested by Epker [41], the mandibu-lar ramus is not lengthened during counterclock-

wise rotation of the distal segment, and thepterygomandibular sling is not stretched(Fig. 10) if the mandible is advanced.

Neuromuscular adaptation. The postoperativeadaptation of the neuromusculature after most

orthognathic procedures is good. Backward rota-tion of the ramus (proximal segment) may stretchthe medial pterygoid muscle and stylomandibular

ligament attached at the medial side of the ramus,however (see Figs. 9 and 10). The muscle and


Fig. 7. This 20-year-old patient had a severe class II anterior open bite as a result of a short mandibular ramus. The

typical soft tissue, skeletal, and dental characteristics of patients who have open bite and short mandibular rami are

exhibited (A–D). The presurgical orthodontic treatment consisted of retraction of the upper and lower incisor teeth, level

and alignment, and coordination of both dental arches (E). A functional occlusion was established by mandibular

advancement, and an aesthetic chin contour was achieved by advancement and slight downgraft of the chin by a genio-

plasty (H). The posttreatment results 3 years after debanding (F–I).


Fig. 8. The medial side of the mandible demonstrates the sagittal split osteotomy performed through the lower border of

the body and posterior border of the ramus of the mandible (the so-called ‘‘long split’’) (A). The mandible is advanced by

10 mm and rotated counterclockwise by 3.5 mm at the incisor area, which increases the ramus height by 8 mm (B).

ligament attachment also interfere with posteriorrepositioning the distal segment and lead tobackward and downward rotation of the proximal

segment. Stripping the attachments of the medialpterygoid muscle and stylomandibular ligamentfrom the medial side of the angle of the mandible

during surgery is recommended. The length of thetemporalis muscle is also influenced by backwardrotation of the ramus, and control of the proximal

segment is important to facilitate neuromuscularadaptation (Fig. 11).

Muscle orientation. Muscular adaptation is least

possible when muscle orientation is changed. The

changes in the inclination of the mandibularramus alter the orientation of the mandibularelevators. The three masseter muscle bundle

groups and temporalis muscle with their respec-tive attachments and orientations are demon-strated in Fig. 11.

There is a paucity of studies in the literatureregarding the long-term postoperative stabilityafter surgical closure of anterior open bite dento-

facial deformities by surgical counterclockwiserotation of the mandible. However, skeletalstability after counterclockwise rotation of themandible as part of the rotation of the maxillo-

mandibular complex was studied and reported by

Fig. 9. The medial view of the mandible illustrates the attachments of the medial pterygoid muscle and stylomandibular

ligament and their relation to the medial aspect of the sagittal osteotomy design, which includes the lower and posterior

border [37,38]. Counterclockwise rotation of the distal segment increases the height of the ramus and stretches the muscle

and ligament (A). When the osteotomy is performed according to the Epker [40] modification, the height of the ramus is

not increased and the muscle and ligament are not stretched (B). The arrow indicates the anterior border of the

pterygomandibular sling.


Fig. 10. The medial side of the mandible illustrates the sagittal osteotomy. The horizontal osteotomy is extended just

posterior to the lingula, whereas the vertical osteotomy is performed through the buccal cortex and extended through

the inferior border to include the medial cortex. This osteotomy design results in the medial osteotomy running

from just posterior to the lingula downward to the lingual side of the vertical osteotomy (the so-called ‘‘short split’’)

(A). The mandible is advanced by 10 mm and rotated counterclockwise by 3.5 mm at the lower incisor tip. Note that

there is no increase in the posterior ramus height (B).

Reyneke [42] and Chemello and colleagues, [43].With this surgical design, an anterior open biteis created by surgical counterclockwise rotation

of the maxillary occlusal plane. The counterclock-wise rotation of the maxilla is followed by thesurgical rotation of the mandible. Long-termpostoperative stability in both studies was found

to be comparable to other mandibular surgicalprocedures.

Open bite secondary to a combination of verticalmaxillary excess and short mandibular ramus

Many individuals with anterior open bite may

display a combination of the clinical, dental, and

Fig. 11. The deep muscle group of the masseter tends to have a vertical orientation, whereas the superficial masseter

muscle groups have a more oblique orientation (A). The orientation of the temporalis muscle is more vertical, and

any posterior rotation of the proximal segment changes the orientation and length of the muscle (B).


cephalometric features of excessive vertical de-velopment of the maxilla and deficient develop-ment of the mandibular rami. In these cases the

treatment objectives should be aimed at address-ing the specific skeletal, soft tissue, and dentalproblems as discussed for each of the twogroups.

Open bite secondary to short mandibular ramuswith condylar resorption

Any process of resorption of the condyle alters

the morphology of the condyle and its position inthe glenoid fossa. Resorption of the condyles andconsequent shortening of the mandibular rami

lead to the development of a class II anterior openbite malocclusion. When considering correction ofan anterior open bite caused by resorption of thecondyle, the clinician should differentiate between

idiopathic condylar resorption, degenerative jointdisease, and rheumatic arthritis with destructionof the condyle.

Idiopathic condylar resorption (condylysis). Al-though condylysis may occur in any patientpopulation, it often presents in relatively young

caucasian women with high mandibular andocclusal plane angles and develops into a class IIanterior open bite malocclusion. The anterior

open bite usually develops progressively with nopain or hypomobility. The process is usually self-limiting and may last from 6 months to 2 years. Itis thought that the resorption may be related to

chronic excessive loading of the mandibularcondyle, which produces progressive remodelingof the condyle. There are two important aspects

when planning the correction of the existingdentofacial deformity: (1) ensuring that the re-sorption process is inactive and (2) treating the

deformity in such a way that the loads on thecondyles are not increased. To establish whetherthe condition is still active, the patient’s previous

dental records, cephalometric radiographs, andocclusal models can be compared with currentrecords. An alternative method, such as a radio-isotope bone scan of the temporomandibular

joints, may help to detect the presence of anyresorptive activity in the condyle. Treatmentshould be delayed until the disease becomes

quiescent.Surgical correction should focus on the max-

illa, and mandibular advancement should be

avoided if possible. Maxillary setback, whichmay compromise the aesthetic outcome, mayhave to be considered. If mandibular surgery

cannot be avoided, however, use of rigid fixationis not recommended but rather a period of 3 to 4weeks of intermaxillary fixation. Any orthodontic

treatment, such as class III elastics, that increasesthe loading of the condyles (and could reinitiatethe condylar resorption process) should beavoided.

Degenerative joint disease (osteoarthrosis). Osteo-arthrosis of the temporomandibular joint is not anacute entity but rather a progressive degenerative

disease that alters the position, morphology, andphysiology of the bony joint structures. It involvesthe progressive uncontrollable degeneration of the

mandibular condyle, and unfortunately, thediagnosis and treatment selection are complicatedby the variability of the rate of progression of

resorption. Patients experience chronic signs ofjoint pain, crepitus, and hypomobility with pe-riods of acute exacerbations. It may be possible toobtain short-term relief of the symptoms by

conservative partial reconstruction of the jointand orthognathic surgery; however, in mostpatients the natural progression of the degenera-

tive process leads to recurrence of the open biteand increasing joint symptoms. Total joint re-placement combined with orthognathic correction

of the dentofacial deformity is often the finaltreatment solution.

Treatment planning for combined orthog-

nathic surgery and total joint replacement doesnot differ from conventional orthognathic treat-ment planning. There is, however, a limitedamount of mandibular advancement that can be

obtained by the placement of a joint prosthesis.To maintain satisfactory contact between theimplant and the mandibular ramus, the advance-

ment should be limited to 7 to 8 mm.

Summary

Development of an anterior open bite ispredominantly the result of an altered growthpattern that involves excessive vertical growth of

the maxilla, lack of vertical mandibular ramusdevelopment, or both. Successful correction ofanterior open bite dentofacial deformities requires

careful assessment of the specific anatomiclocation of the discrepancy and an understandingof all factors that may influence the stability of

results. The flowchart (Fig. 12) summarizes thesuggested principles of surgical orthodontic treat-ment of anterior open bite dentofacial deformities.


Anterior open bite

Posterior verticalmaxillary excess

Short mandibularramus

Le Fort I Osteotomy(superior repositioning)

Bilateral sagittalsplit osteotomy

Correction of APdiscrepancy with

maxilla and BSSO(if necessary)

Monitor condyle

Condylar resorptionNormal condyle orfractured condyle

If stable

If resorptionprogressive

Condylar replacement

Mandibular closed rotation

Genioplasty

Acceptablemandibular AP

position

Fig. 12. The flowchart summarizes the suggested treatment philosophies that focus on anterior open bite correction, in

which surgical correction is aimed at the specific anatomic location of the discrepancy.

References

[1] Haryett RD, Hansen FC, Davidson PO.

Chronic thumb sucking. Am J Orthod 1970;57:

164–78.

[2] Chung CS, Niswander JD, Runck DW. Genetic and

epidemiologic studies of the oral characteristics in

Hawaii’s schoolchildren. II. Malocclusion. Am J

Hum Genet 1971;23:471–95.

[3] Corrucini RS, Potter RHY. Genetic analysis of oc-

clusal variation in twins. Am J Orthod 1980;78:

140–54.

[4] Linder-Aronson S, Woodside D. Factors affecting

the facial and dental structures in excess face height:

malocclusion, etiology, diagnosis, and treatment.

Chicago: Quintessence Pub Co; 2000. p. 1–33.

[5] Proffit WR, Fields HW, Nixon WL. Occlusal forces

in normal and long face adults. J Dent Res 1983;62:

566–70.

[6] Proffit WR, Fields HW. Occlusal forces in nor-

mal and long face children. J Dent Res 1983;

62:571–4.

[7] Turvey TA, Journot V, Epker BN. Correction of

anterior bite deformity: a study of tongue function,

speech changes, and stability. J Max Fac Surg

1976;4:93–101.

[8] Solow B, Siersback-Nielsen PW, Greve E. Airway

adequacy, head posture and cranial morphology.

Am J Orthod 1984;86:214–23.

[9] Slow B, Sonnesen L. Head posture and malocclu-

sion. Eur J Orthod 1998;20:685–93.

[10] McNamara JA. Early intervention in the transverse

dimension: is it worth the effort? Am J Orthod

Dentofacial Orthop 2002;121:572–4.

[11] Sherwood KH, Burch JG, Thomson WJ. Closing

open bites by intruding molars with titanium mini-

plate anchorage. Am J Orthod Dentofacial Orthop

2002;122(6):593–600.

[12] Siato I, Amaki M, Hanada K. Non surgical treat-

ment of adult open bite using edgewise appliance

combined with high-pull headgear and class III elas-

tics. Angle Orthod 2005;75(2):277–83.

[13] Kuroda S, Katayama A, Takano-Yamamoto T.

Severe anterior open-bite using titanium screw

anchorage. Angle Orthod 2004;74(4):558–67.

[14] Carano A, Siciliani G, Bowman SJ. Treatment of

skeletal open bite with a device for rapidmolar intru-

sion: a preliminary report. Angle Orthod 2005;75(5):

736–46.

[15] Hamamci N, Basaran G, Sahin S. Non-surgical

correction of an adult skeletal class III and open-

bite malocclusion. Angle Orthod 2006;76(3):527–32.

[16] Erverdi N, Usumez S, Solak A. New generation

open-bite treatment with zygomatic anchorage.

Angle Orthod 2006;76(3):519–26.

[17] Kuster R, Ingervall B. The effect of treatment of

skeletal open bite with two types of bite-blocks.

Eur J Orthod 1992;14(6):489–99.

[18] Mao JJ. Mechanobiology of craniofacial sutures.

J Dent Res 2000;81:810–6.

[19] Handelman CS,Wang C, BeGole EA, et al. Nonsur-

gical rapid maxillary expansion in adults: report on


47 cases using the Haas expander. Angle Orthod

2000;70:129–44.

[20] de Freitas MR, Beltrao RT, Janson G, et al. Long-

term stability of anterior open bite extraction

treatment in the permanent dentition. Am J Orthod

Dentofacial Orthop 2004;125(2):78–87.

[21] JansonG, Valarelli FP, Henriques JF, et al. Stability

of anterior open bite nonextraction treatment in the

permanent dentition. Am J Orthod Dentofacial

Orthop 2003;124(3):265–76.

[22] Cozza P, Mucedero M, Baccetti T, et al. Early or-

thodontic treatment of skeletal open-bite malocclu-

sion: a systematic review. Angle Ortod 2005;75(5):

707013.

[23] Behrents RG. Growth in the aging facial skeleton-

Monograph #17: Craniofacial Growth Series. Ann

Arbor: The University of Michigan, Center for

Human Growth and Development; 1985.

[24] Fotis V,Melsen B,Williams S. Vertical control as an

important ingredient in the treatment of severe

sagittal discrepancies. Am J Orthod 1984;86:224–32.

[25] Reyneke JP. Vertical variation in skeletal open bite:

a classification for surgical planning. J Dent Ass S

Africa 1988;43:465–72.

[26] Arnett GW, Bergman RT. Facial keys to orthodon-

tic diagnosis and treatment planning. Part I. Am J

Orthod Dentofacial Orthop 1993;103:299–312.

[27] Profitt WR, Turvey TA, Phillips C. Orthognathic

surgery: a hierarchy of stability. Int J OrthodOrthog

Surg 1996;11(3):191–204.

[28] Jacobs JD, Bell WH, Williams C, et al. Control of

the transverse dimension with surgery and ortho-

dontics. Am J Orthod 1980;77:284–306.

[29] Bell WH, Jacobs JD, Quejada JG. Simultaneous

repositioning of the maxilla, mandible and chin.

Am J Orthod 1986;89:28–50.

[30] Koudstaal MJ, Poort LJ, Van der Wal KGH, et al.

Surgically assisted rapid maxillary expansion

(SRME): a review of the literature. Int J Oral Max-

illofac Surg 2005;34(7):709–14.

[31] Bloomquist DS. Mandibular narrowing: advantage

in transverse problems. J Oral Maxillofac Surg

2004;62(3):365–8.

[32] Alexander CD, Bloomquist DS, Wallen TR. Stabil-

ity of mandibular constriction with a symphyseal

osteotomy. Am J Orthod Dentofacial Orthop

1993;103(1):15–23.

[33] Phillips C, MedlandWH, Fields HW, et al. Stability

of surgical maxillary expansion. Int J Adult Ortho-

don Orthognath Surg 1992;7:139–46.

[34] Carlson DS, Ellis E, Dechow PC, et al. Short-term

stability and muscle adaptation after mandibular

advancement surgery with and without suprahyoid

myotomy in juvenile Macaca mulatta. Oral Surg

Oral Med Oral Pathol 1983;68:135–49.

[35] Wessberg GA, Schendel SA, Epker BN. The role of

suprahyoidmyotomy in surgical advancement of the

mandible via sagittal split ramus osteotomy. J Oral

Maxillofac Surg 1982;40(5):273–7.

[36] Epker BN, Wolford LM, Fish LC. Mandibular

deficiency syndrome: surgical considerations for

mandibular advancement. Oral Surg 1978;45:

349–63.

[37] Epker BN, Stella JP, Fish LC. Dentofacial

deformities, integrated orthodontic and surgical

correction. St Louis (MO): Mosby; 1995. p. 186–7.

[38] Trauner R, Obwegeser H. The surgical correction of

mandibular prognathism and retrognathia with

consideration of genioplasty. Oral Surg 1957;10:

787–92.

[39] Dal Pont G. Retromolar osteotomy for the correc-

tion of prognathism. J Oral Surg 1961;19:42–7.

[40] Schendel SA, Epker BN. Results after mandibu-

lar advancement surgery. J Oral Surg 1980;38:

225–8.

[41] Epker BN. Modifications in the sagittal osteotomy

of the mandible. J Oral Surg 1977;35:157–9.

[42] Reyneke JP. Rotation the maxillomandibular com-

plex: an alternative surgical design in orthognathic

surgery [academic dissertation]. Tampere, Finland:

University of Tampere, Institute of Regenerative

Medicine; 2006.

[43] Chemello PD, Wolford LM, Buchang PH. Occlusal

plane alteration in orthognathic surgery. Part II:

long term stability of results. Am J Orthod Dentofa-

cial Orthop 1994;104:434–40.

Date post:	07-May-2015
Category:	Health & Medicine
Upload:	kptaiping-perak
View:	1,398 times
Download:	3 times

Aob correct by le fort i or bsso

Health & Medicine