CASE REPORT

Elimination of transverse dental compensation iscritical for treatment of patients with severefacial asymmetry

Toshiko Sekiya,a Yoshiki Nakamura,b Takashi Oikawa,a Hiroaki Ishii,c Ayao Hirashita,d and Kan-ichi Setoe

Yokohama, Japan

This case report describes the importance of eliminating transverse dental compensation during preoperativeorthodontic treatment for a patient with severe facial asymmetry. The patient, a 17-year-old Japanese woman,had severe facial asymmetry involving the maxilla and the mandible, and extreme transverse dental compen-sation of the anterior and posterior teeth in both arches. Therefore, the main treatment objectives wereelimination of the transverse dental compensation by orthodontic treatment and correction of the morphologyof the maxilla and the mandible by orthognathic surgery. The preoperative orthodontic treatment resulted insufficient elimination of the transverse dental compensation and movement of the teeth into their properpositions so that basal bone firmly supported them. LeFort I osteotomy and sagittal split ramus osteotomywere performed to correct the skeletal morphology. Facial asymmetry was dramatically improved, and a favor-able occlusion was obtained. At 1 year 8 months after the surgical orthodontic treatment, the facial symmetryand occlusion remained favorable. The results suggest that sufficient elimination of transverse dental compen-sation in the maxillary and mandibular arches during preoperative orthodontic treatment is requisite forsuccessful treatment of severe facial asymmetry. (Am J Orthod Dentofacial Orthop 2010;137:552-62)

Facial asymmetry is highly visible, can degradequality of life, and is often a chief complaint oforthodontic patients.1-3 Patients with severe fa-

cial asymmetry are generally treated with a combinationof orthodontic and orthognathic surgical therapies, notonly to improve their occlusion, but also to improvetheir facial esthetics.4-6 With such treatment, it is diffi-cult to develop a plan to improve facial esthetics, be-cause patients with severe facial asymmetry also oftenhave extreme transverse dental compensation.5-12 Themaxillary incisors and posterior teeth are usually in-clined to the deviated side, and the mandibular incisorsand posterior teeth are inclined to the contralateral sideto maintain normal interarch positioning under trans-verse jaw relationships.4,11-14 In such cases, it is criticalto eliminate the extreme transverse dental compensation

From the School of Dental Medicine, Tsurumi University, Yokohama, Japan.aInstructor, Department of Orthodontics.bAssistant professor, Department of Orthodontics.cAssociate professor, Department of Oral and Maxillofacial Surgery.dProfessor and chairman, Department of Orthodontics.eProfessor and chairman, Department of Oral and Maxillofacial Surgery.

The authors report no commercial, proprietary, or financial interest in the

products or companies described in this article.

Reprint requests to: Toshiko Sekiya, Department of Orthodontics, Tsurumi Uni-

versity School of Dental Medicine, 2-1-3 Tsurumi, Tsurumi-ku, Yokohama,

230-8501, Japan; e-mail, sekiya-t@tsurumi-u.ac.jp.

Submitted, February 2007; revised and accepted, October 2007.

0889-5406/$36.00

Copyright � 2010 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2007.10.064

552

of the maxillary and mandibular teeth6,7 and move themback to the proper positions for basal bones to firmlysupport them.7,10 If this is inadequately done, it willbe impossible to obtain sufficient correction of theasymmetry and the occlusion.6,7

We treated a patient with severe facial asymmetry,using orthodontic and orthognathic approaches, and im-proved her quality of life.

DIAGNOSIS AND ETIOLOGY

The patient was a 17-year-old Japanese woman. Herchief complaint was facial asymmetry. According to theinterview, the facial asymmetry was pointed out by herfamily doctor and first became obvious when she wasabout 11 years old. Because there was no history of in-jury to her head or the jaw, and no relevant family his-tory, the cause of her facial asymmetry was unknown.In the frontal view, severe facial asymmetry was obvi-ous; the mandible was deviated to the left. In the lateralview, a convex facial profile was noted (Fig 1).

The midline of the maxillary arch was deviated about1 mm to the right from the facial midline, whereas themidline of the mandibular arch was deviated 3 mm tothe left (Fig 2). The maxillary incisors were inclinedto the left, and the mandibular incisors were inclined tothe right. Overbite and overjet were 4.5 and 4.0 mm,respectively. The maxillary right caninewas blocked labi-ally, and a scissors-bite was observed between the

Fig 1. Pretreatment facial and intraoral photographs.

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maxillary and mandibular right first premolars. The molarrelationships were Class I on the right and Class II on theleft. The mandibular arch was asymmetric, with severelingual inclination of the mandibular left molars and pre-molars. In contrast, the maxillary right molars had an ex-treme palatal inclination. There was moderate crowdingin both arches, and the maxillary and mandibular arch-length discrepancies were –9 and –6 mm, respectively.

The patient had no temporomandibular joint (TMJ)disorder symptoms at the examination, although she hada history of occasional clicking sounds in the left TMJ.Magnetic resonance imaging showed anterior articulardisc displacement without reduction, and computed to-mography (CT) showed osteoarthrosis in the left TMJ.

A panoramic radiograph showed that the maxillarycentral incisors had short roots. No pathologic lesions ofthe alveolar bone were observed (Fig 3). Lateral cephalo-metric evaluation showed a skeletal Class II jaw relation-ship (ANB, 8.1�) with mandibular retrognathia (SNB,

72.3�). The mandibular plane angle was steep, and the ra-mus was retroclined. The maxillary and mandibular cen-tral incisors were inclined lingually (Table). Both themaxilla and the mandible exhibited severe deviation onthe frontal cephalogram and the 3D CT image (Fig 3).Menton was deviated to the left 12 mm from the midsag-ittal plane (facial midline). The difference in height be-tween the left and right molars was 5 mm, and the cantof the occlusal plane was 4.5�. The patient was diagnosedwith a transverse jaw deformity of the maxilla and mandi-ble with skeletal Class II jaw relationship.

TREATMENT OBJECTIVES

The following treatment objectives were estab-lished: (1) correct the jaw deformities of the maxillaand the mandible; (2) eliminate the transverse dentalcompensation; (3) coordinate the skeletal and dentalmidlines; (4) correct and coordinate the maxillary and

Fig 3. Pretreatment radiographs.

Fig 2. Pretreatment dental casts.

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Fig 4. Presurgical intraoral photographs. The transverse dental compensation of the anterior andposterior teeth was eliminated, and the left buccal segments showed lateral crossbite.

Table. Cephalometric measurements

Norm (SD) Pretreatment (17 y 3 mo) Posttreatment (20 y 7 mo) Postretention (22 y 3 mo)

Angular (�)SNA 81.3 (3.0) 80.4 80.0 79.8

SNB 79.2 (3.0) 72.3 74.0 73.9

ANB 2.1 (2.1) 8.1 6.0 5.9

Facial angle 87.3 (3.1) 80.5 82.0 81.9

FMA 27.1 (5.2) 39.8 40.0 39.8

U1-SN 104.3 (5.8) 83.8 94.0 94.8

FMIA 58.0 (6.0) 51.9 51.5 52.5

IMPA 93.0 (6.2) 88.3 87.5 88.0

Linear (mm)

A0-Ptm0 50.1 (3.2) 46.7 46.2 46.0

Gn-Cd 120.8 (5.2) 105.9 109.3 109.3

Pog0-Go 80.0 (4.7) 70.5 71.7 71.6

Cd-Go 61.2 (4.3) 49.9 52.1 52.0

Norm, Reference norm of Japanese women.

S, Sella; N, nasion; A, A-point; B, B-point; SN, sella-nasion plane; Facial angle, angle between FH plane and nasion-pogonion plane; FMA, angle

between FH plane and mandibular plane; U1, axial inclination of maxillary central incisor; FMIA, angle between FH plane and axial inclination of

mandibular central incisor; IMPA, angle between axial inclination of mandibular central incisor and mandibular plane; Gn, gnathion; Cd, condylion;

Pog0, perpendicular from pogonion to mandibular plane; Go, gonion.

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mandibular arch forms; (5) correct the irregularity of theteeth (eliminate the arch-length discrepancy); and (7)improve the facial asymmetry.

TREATMENT ALTERNATIVES

Several treatment options were considered. The firstwas extraction of the maxillary and mandibular first pre-molars during preoperative orthodontic treatment. This

option would make it easy to coordinate the maxillaryand mandibular arch forms. But coordinating the dentalmidline with the skeletal midline of the mandible wouldbe difficult. In this option, facial asymmetry would bedifficult to correct during the orthognathic surgery.The second option was extraction of the maxillary firstpremolars and the mandibular left first premolar. Al-though this option might cause a Class II molar relation-ship on the right side, it would be beneficial for

Fig 5. Posttreatment facial and intraoral photographs.

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eliminating the transverse dental compensation of man-dibular incisors and coordinating the dental midlinewith the skeletal midline of mandible.

The first surgical option was a mandibular osteot-omy only.15-17 The second option was 2-jaw surgery:Le Fort I and mandibular osteotomies. The first optionwould not sufficiently improve the facial asymmetry, al-though the surgical intervention was limited to the man-dible. On the other hand, 2-jaw surgery would be muchmore effective for improving the facial symmetry of themaxilla and the mandible.5,18,19

TREATMENT PLAN

In the consultation, the patient and her parentsselected the following treatment plan.

1. Preoperative orthodontic treatment to include ex-traction of the maxillary first premolars and the

mandibular left first premolar, elimination of thearch length discrepancy, alignment and decompen-sation of the maxillary and mandibular teeth, archcoordination, and coordination of the dental mid-lines with the midlines of the jaws.

2. Orthognathic surgery to include Le Fort I osteot-omy to correct the asymmetry of the maxilla withiliac bone grafting and bilateral sagittal split ramusosteotomy (SSRO) to correct the mandibular devi-ation.

3. Postoperative orthodontic treatment to include fineadjustment of the occlusion and muscle training.

4. Retention.

TREATMENT PROGRESS

When the patient was 17 years old, the maxillary firstpremolars and mandibular left first premolar were

Fig 6. Posttreatment dental casts.

Fig 7. Posttreatment radiographs.

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Fig 8. Dental casts cut off at the maxillary and mandibular first molars. A, Pretreatment casts showextreme transverse dental compensation of the maxilla and mandible; B, posttreatment casts showthat the transverse dental compensation of the maxillary and mandibular first molars was eliminated,and symmetry of molar inclination was obtained. Solid line, axis of the first molars.

Fig 9. Tracings of the frontal cephalograms. Skeletal symmetry was obtained with improvement ofthe canted occlusal plane and correction of the mandibular deviation.

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extracted, and 0.018 3 0.025-in standard edgewise appli-ances were placed in both arches. The arches were leveledand aligned, with several replacements of archwires. Themaxillary incisors were moved slightly to the left. Themandibular incisors were also moved to the left to elimi-nate the transverse dental compensation and coordinatethe dental midline with the midline of the mandible. Asa result, the dental midline was moved until it was approx-imately 11 mm to the left of the facial midline.

Futhermore, the dental compensation of the buccalsegments of the maxillary and mandibular arches waseliminated. A set of 0.017 3 0.025-in stainless steelarchwires with third-order bends was used to eliminatethe transverse dental compensation.

At the end of this treatment, the left buccal segmentsexhibited a lateral crossbite, and the teeth in both archeswere moved to positions where the basal bone firmlysupported them, making it possible for surgical correc-tion of the maxilla and the mandible (Fig 4).

When the patient was 20 years 3 months old, theLe Fort I osteotomy and bilateral SSRO with titaniumminiplate fixation were performed to correct the jawdeformities. The maxilla was rotated clockwise tocorrect the canted occlusal plane of the maxillaryarch, and iliac bone was grafted onto the left disjunctionregion. The left maxillary alveolar bone was reposi-tioned 5 mm inferiorly. The body of the mandiblewas moved 10.5 mm to the undeviated side, with

Fig 10. Superimposition of pretreatment (solid lines)and posttreatment (dashed lines) lateral cephalometrictracings.

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a 6.5-mm advancement on the left side and a 7.5-mmsetback on the right side.

Maxillomandibular fixation was maintained for 10days, with neuromuscular and occlusal rehabilitationfor 1 month. Then, arch coordination and interdigitationwere adjusted for 4 months, the edgewise applianceswere removed, and circumferential retainers wereused for retention.

TREATMENT RESULTS

The posttreatment photographs and dental castsshowed successful results (Figs 5-7). The frontal viewwas dramatically improved, and the profile was alsoslightly improved, with forward movement of the chinand reduction of upper lip protrusion. Overbite and over-jet were 3.0 mm and 2.0 mm, respectively. Favorable in-terdigitation and a Class I canine relationship betweenthe maxillary and mandibular teeth were obtained, al-though the molar relationships were Class I on the leftand full-cusp Class II on the right. The preoperativeorthodontic treatment sufficiently eliminated the trans-verse dental compensation of the mandibular left molarsand maxillary right molars. In both arches, symmetry ofbuccolingual molar inclinations was obtained, and basalbone firmly supported the molars (Fig 8).

The frontal cephalogram and the 3D CT imagesshowed that the cant of the maxillary occlusal planewas eliminated by the LeFort I osteotomy, and the devi-ation of the mandible was eliminated by the SSRO. Con-sequently, the midlines of the maxilla and mandible

were coordinated with the facial midline (Figs 7 and9). The maxillary incisors showed slight root resorption.There was no sign of TMJ disorder during the treatment.

Superimposition of the pretreatment and posttreat-ment lateral cephalograms showed a slight forwardmovement of the mandible (Fig 10). Cephalometric anal-ysis indicated that the ANB angle had decreased from8.5� to 6.5� because of a slight increase in the SNB angle.The occlusal plane angle had decreased to approximately5�, and the U-1 to SN angle had increased (Table). Radio-graphic examination showed slight root resorption of themaxillary incisors (Fig 7). There was no sign of a tempo-romandibular disorder during the treatment.

After 1 year 8 months of retention (ending 2 years af-ter orthognathic surgery), the facial symmetry and occlu-sion were well maintained, and the patient was satisfiedwith the treatment results (Figs 11 and 12, Table).

DISCUSSION

It is important to understand the components of fa-cial asymmetry for diagnosing and planning surgical or-thodontic treatment.20 Facial asymmetry is generallyclassified into 3 patterns, depending on the area af-fected: craniofacial skeleton, both maxilla and mandi-ble, and mandible only. In this patient, the frontalcephalometric analysis indicated that the facial asym-metry extended over the maxilla and the mandiblewith transverse and vertical skeletal asymmetry. Insuch cases of facial asymmetry, transverse dental com-pensation is frequently observed to maintain the dentalocclusion.5-12 The magnitude of transverse dental com-pensation generally varies to the same extent as the pa-tient’s skeletal deformity,5 and many studies of skeletalasymmetry have shown that transverse dental compen-sation is statistically correlated with transverse skeletalasymmetry.12-14,20 Our patient had extreme transversedental compensation of the anterior and posterior teethas a consequence of the severe skeletal asymmetry.The maxillary incisors and molars were inclined to thedeviated side, and the mandibular incisors and molarswere inclined to the contralateral side. The mandibularleft posterior segment was extremely inclined to theright; this prevented the formation of a crossbite, despitethe severe lateral deformities of the maxilla and themandible. Furthermore, the mandibular incisors werealso inclined to the right, and the mandibular right lat-eral incisor was pushed out from the arch. This seemedto be a reaction of the body to maintain normal interarchpositioning even with a distorted jaw relationship.

The primary goal of preoperative orthodontic treat-ment is to eliminate the transverse dental compensationfor the skeletal deformity.5,7 If the transverse dental

Fig 11. Postretention facial and intraoral photographs.

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compensation is left during preoperative orthodontictreatment, the facial asymmetry will remain, even thoughthe surgery produces satisfactory occlusion.6,7 Therefore,it is critical to eliminate the dental compensation ortho-dontically6,7,21 and to move the teeth to their proper po-sitions so that basal bone supports them.7,10 This makesit possible to move the maxilla and the mandible intotheir proper positions during orthognathic surgery.10

The preoperative orthodontic treatment includedelimination of transverse dental compensation and coor-dination of the dental and skeletal midlines. In the max-illary arch, the elimination of the transverse dentalcompensation and the correction of the dental midlineinvolved extraction of both maxillary first premolars.In the mandibular arch, the treatment was somewhatcomplicated. It was necessary to move the dental mid-line 7 to 8 mm to the left to make the dental midline co-incident with that of the mandible; therefore, only themandibular left premolar was extracted. The dental

midlines of the maxillary and mandibular arches werecoordinated with the midlines of the maxilla and mandi-ble, respectively. Asymmetric extraction is an effectiveapproach to correct transverse decompensation so thatthe incisors can be retracted more on one side than onthe other, and the midline can be shifted in the desireddirection.5 The transverse dental compensation of theposterior teeth was completely eliminated by torquecontrol, and coordination of both arches was obtained.The posterior teeth were seated firmly on the basalbone of the maxilla and the mandible, making it easierto position them during the orthognathic surgery. Thepreoperative orthodontic treatment enabled sufficientcorrection of the jaw deformities during the orthog-nathic surgery and dramatically improved the facialasymmetry. This indicates that elimination of transversedental compensation during preoperative orthodontictreatment is a requisite for successful correction ofsevere facial asymmetry.

Fig 12. Postretention radiographs.

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The combination of Le Fort I osteotomy and SSROis an effective method for correcting facial asymmetryextending over the maxilla and the mandible.5,18,19

The Le Fort I osteotomy with iliac bone grafting to elim-inate the canted occlusal plane made it possible to cor-rect the maxillary asymmetry. This procedure made iteasier to reposition of the mandible during the SSRO.

For our patient, the postoperative treatment took only4 months—a very short period—suggesting that the like-lihood of skeletal relapsewas small, despite the great skel-etal changes. The preoperative elimination of transversedental compensation appears to have contributed to thestability of facial symmetry and occlusion after treatment.Early muscle training after the orthognathic surgery couldalso have contributed to the stability.

CONCLUSIONS

This case suggests that sufficient elimination of ex-treme transverse dental compensation of the anteriorand posterior teeth in both arches during preoperativeorthodontic treatment is a requisite for the successfultreatment of severe facial asymmetry and stabilizationof the occlusion after orthognathic surgery.

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