CASE REPORT

Correction of an asymmetric maxillary dental archby alveolar bone distraction osteogenesis

Seigo Ohba,a Takayoshi Tobita,b Nobutaka Tajima,c Kyoko Matsuo,d Noriaki Yoshida,e and Izumi Asahinaf

Nagasaki, Japan

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This case report describes a new surgical orthodontic approach involving alveolar bone distraction osteogenesisfor correction of an asymmetric maxillary dental arch. The treatment was combined with conventional orthog-nathic surgery to improve the mandibular lateral deviation. This new treatment strategy produced an ideal dentalarch and a symmetric facial appearance efficiently and effectively. (Am J Orthod Dentofacial Orthop2013;143:266-73)

An asymmetric dental arch associated with a skel-etal problem often results in an asymmetricfacial appearance. Improving the distorted facial

appearance is one of the most critical objectives oforthognathic surgery. Several treatment techniqueshave been introduced for an asymmetric dental arch. Aconventional nonsurgical orthodontic treatment givesan acceptable outcome if well-planned force mechanicsare provided. However, they could induce root blunting,resorption, or fenestration during the treatment if the af-fected tooth-bone relationships are poor.1,2 Moreover,the treatment duration might be prolonged withtraditional orthodontic treatment, because of thosemechanical and physical complications. On the otherhand, a surgical approach such as an osteotomy cancorrect skeletal problems immediately, althoughfixation of bone specimens sometime becomes difficultbecause it requires dexterous manipulation for fitting.

rer, Department of Regenerative Oral Surgery, Graduate School of Biomed-ciences, Nagasaki University, Nagasaki, Japan; Division of Dentistry andurgery, Department of Sensory and Locomotor Medicine, Faculty of Med-ciences, University of Fukui, Eiheiji-cho, Japan.rer, Department of Regenerative Oral Surgery, Graduate School of Bio-al Sciences, Nagasaki University, Nagasaki, Japan.tant professor, Department of Regenerative Oral Surgery, Graduate Schoolmedical Sciences, Nagasaki University, Nagasaki, Japan.tant professor, Department of Orthodontics and Dentofacial Orthopedics,ate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.ssor, Department of Orthodontics and Dentofacial Orthopedics, Graduatel of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.ssor, Department of Regenerative Oral Surgery, Graduate School of Bio-al Sciences, Nagasaki University, Nagasaki, Japan.uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Seigo Ohba, 1-7-1 Sakamoto, Nagasaki 852-8588 Japan;l, seigoohba@gmail.com.itted, December 2010; revised and accepted, September 2011.5406/$36.00ight � 2013 by the American Association of Orthodontists./dx.doi.org/10.1016/j.ajodo.2011.09.013

Furthermore, even in a comparably simple proceduresuch as a corticotomy, sometimes the bone fixation canbe challenging as well. Therefore, we suggest our newstrategy, which overcomes the above-mentioned disad-vantages, for treatment of an asymmetric dental arch.

DIAGNOSIS AND ETIOLOGY

An 18-year-old Japanese woman was referred to theDepartment of Orthodontics at Nagasaki University Hos-pital in Japan for correction of her facial asymmetry. Herfrontal facial appearance was not symmetric because oflateral deviation of the mandible, and the lateral profilewas concave with normal facial height. The maxillarydental arch showed asymmetry because the right poste-rior teeth from the first premolar to the second molarwere palatally inclined, but there was no posterior cross-bite. The basal alveolar ridge on the maxillary right wascollapsed to the palatal side as well. Overjet was 2.5mm, and overbite was 2.0 mm. The mandibular midlinewas shifted 4 mm to the left. The molar relationshipwas Class I on the right and Class II on the left side. Thecanine relationships were Class III on the right and ClassI on the left (Figs 1 and 2). The panoramic radiographshowed that all permanent teeth were present exceptthe first and third molars on the mandibular left side(Fig 3). The cephalometric analysis showed that althoughthe values of the SNA and SNB angles were within 1 SD,the ANB was �0.4�, showing mild mandibular progna-thia. In addition, the facial angle, which represents themandibular position, and the A-Bplane,which representsthe maxillomandibular relationship, were 88.3� (.1 SD)and �0.9 mm (.1 SD), respectively (Table and Fig 4),showing a protruded mandible as well. The posteroante-rior cephalometric radiograph detected no cant of themaxilla. Based on these findings, the patient was

Fig 1. Pretreatment facial and intraoral photographs.

Fig 2. Pretreatment dental casts.

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Fig 3. Pretreatment panoramic radiograph.

Fig 4. Pretreatment cephalometric tracing.

Table. Cephalometric analysis

Mean SD Patient SDFH to SN plane (�) 6.2 5.9 5.8SNA (�) 82.3 3.5 80.6SNB (�) 78.9 3.5 81Facial angle (�) 84.8 3.1 88.3 *Gonial angle (�) 131 5.6 121.6 *Ramus angle (�) 83 4.4 88.4 *A-B plane (�) �4.8 3.5 �0.9 *ANB (�) 3.4 1.8 �0.4 *U1 to FH plane (�) 111.1 5.5 117.1 *L1 to mandibular plane (�) 96.3 5.8 84.8 *

*Patient's value is 61 SD.

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diagnosed with a skeletal Class III malocclusion withmandibular prognathism, facial asymmetrywithmandib-ular deviation, and an asymmetric maxillary dental arch.

TREATMENT OBJECTIVES

The main objectives of this orthodontic treatmentwere to correct the facial and dental asymmetries andthe maxillomandibular relationship. Therefore, theorthodontic treatment objectives were to (1) achievea symmetric maxillary arch form, repositioning the ret-roclined maxillary right premolars and molars and theaccompanying collapsed alveolar ridge by alveolarbone distraction osteogenesis; (2) establish a Class Imutually protected occlusion; and (3) improve thefacial balance and deviation combined with orthog-nathic surgery.

TREATMENT ALTERNATIVES

Intraoral vertical ramus osteotomy was selected tocorrect the lateral deviation of the mandible. Genioplastywas also required to correct the facial imbalance. Sincethere was no cant or rotation of the maxilla, a LeFort Iosteotomy was not necessary. The following 3 treatmentoptions for the asymmetric maxillary dental arch wereconsidered for this patient.

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1. Conventional orthodontic treatment could be per-formed to obtain an ideal dental arch form.Although this would cause minimum physical strainon the patient, the possible risks such as root blunt-ing, resorption, or fenestration would be induced bytooth rotation and uprighting during orthodontictreatment.3 In addition, for correction of the asym-metric facial appearance, an intraoral vertical ramusosteotomy and a genioplasty would be needed afterthe presurgical orthodontic treatment.

2. All surgical procedures such as alveolar bone osteot-omy from the right first premolar to second molar,plate fixations, and intraoral vertical ramus osteot-omy with genioplasty could be performed at thesame time. This alternative might be a standard pro-cedure for treating such a patient; however, creatingan ideal maxillary arch form to match the mandibu-lar arch is difficult during the surgical procedure,because finding the best-fit positions of bone frag-ments and securing them for ideal relationships iscomplicated.

3. First, corticotomy of buccal and palatal alveolarbones from the first premolar to the second molaron the right side of the maxilla could be performedwith a 2-week time lag. Then the insecure maxillaryright posterior ridge would be moved buccally bya distractor until an ideal arch shape is achieved.Finally, an intraoral vertical ramus osteotomy witha genioplasty would be performed to correct thefacial imbalance. This alternative would require

Journal of Orthodontics and Dentofacial Orthopedics

Fig 5. Photographs of corticotomies.

Fig 6. Progress intraoral photographs.

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a longer treatment time than the second option.However, it had 2 advantages compared withthe other treatment options: the orthodontist orsurgeon can manage the amount of tooth-bonemovement during the distraction until an idealrelationship is achieved; and root blunting, resorp-tion, or fenestration can be prevented because thetooth-bone relationship is maintained during thedistraction.

All 3 alternatives, and their risks and benefits, wereexplained to the patient. After the consultation, the pa-tient, the orthodontist, and the oral surgeon chose thethird strategy to eliminate concerns about prolongedtreatment time and complicated surgical procedures asmentioned above.

TREATMENT PROGRESS

All surgical treatment was performed at the De-partment of Oral and Maxillofacial Surgery at Naga-saki University Hospital in Japan. The corticotomywas performed first on the palatal side of the maxillaryalveolar bone from the first premolar to the secondmolar under local anesthesia. Another corticotomyfor the buccal side was done after 2 weeks, whenthe blood supply to the bony fragment from the pal-atal mucosa had recovered (Fig 5). The distractor

American Journal of Orthodontics and Dentofacial Orthoped

(Hyrax Expansion Screw; Dentaurum, Ispringen, Ger-many) was bonded on the maxillary first premolarsand first molars bilaterally before the second cortico-tomy. After a 1-week latency period, the patientstarted to activate the distractor screw once a day(0.5 mm/day) for 14 days.4 After 2 weeks of distrac-tion, the transverse width of the maxillary arch was in-creased by 6.5 mm. The mandibular dental arch wasmaintained in a symmetric form (Fig 6). After 2months of retention, leveling and alignment were ini-tiated by placing 0.014-in nickel-titanium archwires,followed by 0.016-in nickel-titanium and 0.017 30.022-in stainless steel archwires. The preoperativeprocess, including distraction osteogenesis and itsconsolidation, took 12 months. An intraoral verticalramus osteotomy and a genioplasty were performedunder general anesthesia to obtain a Class I occlusionand a symmetric facial appearance. Jaw-opening exer-cises were started on the second day after surgeryalong with the wearing of vertical elastics in the ante-rior region and Class II elastics in the posterior region.

TREATMENT RESULTS

The posttreatment photographs showed an improvedfacial appearance. The maxillary and mandibular mid-lines are coincident with the patient's facial midline.The occlusion was also improved, and a Class I

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Fig 7. Posttreatment facial and intraoral photographs.

270 Ohba et al

relationship was established (Figs 7-11). Figure 12 showsthe improvement of facial asymmetry. The angles be-tween the ear rods and the external border of the man-dibular ramus on the frontal facial photos at the initialexamination were 67� on the right and 82� on the leftside, showing that the mandible was deviated to theleft. The corresponding values after treatment were71� and 75� on the right and left, respectively, and thedifference was 4�. The decrease in the difference be-tween these numbers before and after surgery confirmedthe improvement in facial symmetry after surgery. Theocclusion remained stable during the 2-year posttreat-ment follow-up period.

DISCUSSION

For this patient, buccal and palatal corticotomies ofthe maxillary right alveolar bone were performed witha 2-week time lag. Then theflexible segment of the dentalarch was moved buccally as 1 unit by a distractor until anideal dental arch form was obtained. Since the alveolarbone was palatally inclined, it had caused the dentalarch-form asymmetry. Typically, changing the shape ofalveolar ridge is seen as a usual bone remodeling process

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during tooth movement.5,6 Even in this patient,a symmetric dental arch and an ideal tooth-bone relation-ship could be obtained through such routine orthodontictreatment. However, if only teeth are moved through thecollapsed alveolar bone with uncontrolled orthodonticmechanics, fenestration of the cortical bone might oc-cur.1,2 Therefore, controlled orthodontic mechanicswith a light force are required for this complicatedsituation, and it usually requires a longer treatment time.

Several authors have agreed that corticotomy inducestoothmovement rapidly because of increased bone turn-over.7-9 According to this statement, the treatmentduration with corticotomy must be shorter thanconventional nonsurgical orthodontic treatment evenfor an asymmetric dental arch like that in this patient.Therefore, moving the teeth and alveolar bone as 1block was chosen in this patient. Consequently, it tookonly 2 years to complete the whole process ofcorticotomies, which included distraction osteogenesisand its retention, presurgical orthodontic treatment,orthognathic surgeries, and postsurgical orthodontictreatment. It was considered to be much shorter thanconventional methods with orthodontics only.

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Fig 9. Posttreatment panoramic radiograph.

Fig 8. Posttreatment dental casts.

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In this patient, the buccalmovement of alveolar bone atthe maxillary right premolar and molar was approximately6.5mm. There were no indications of transverse expansionof the palatalmidline or buccalmovement of the other sideof the maxilla. Therefore, the loosening of the maxillarybone at the affected side by corticotomies was importantto apply the maximum force to the affected side. Thus,the other sideof themaxillary archworked as a rigid anchorto hold the distractor and pushed the affected side to thebuccal aspect effectively without moving itself.

A maxillary osteotomy, including a bipartite or a tri-partite osteotomy of the maxilla, is a well-known

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technique to reconstruct an asymmetric dental archform, but it is necessary to perform the procedure undergeneral anesthesia. Furthermore, patients must stay inthe hospital for a few days. According to Landeset al,10 tripartite osteotomy might be preferable in thistype of patient, because it creates no midline diastema,whereas a bipartite osteotomy does. Although this proce-durewould reduce total treatment time, sometimes it canbe difficult to adapt the bone fragments to their ideal po-sitions during the operation because of the complicatedsurgical techniques.10 When plate fixation is improper,the adjustment after surgery will be difficult. On theother hand, an alveolar bone osteotomy is a simple pro-cedure. This technique is also a well-known and usefulprocedure for placing the alveolar bone into an idealposition with the teeth by rigid fixation simulta-neously.11-14 The maxillary alveolar bone osteotomycan be used as in this patient to achieve an ideal dentalarch. However, it is often difficult to set the bonesegment to the proper position after the osteotomy ortripartite osteotomy that was described above.

In contrast to these conventional surgical methods,a corticotomy is quite simple. Corticotomies of the pala-tal and buccal surfaces can be completed within 1 hourunder local anesthesia for an outpatient (Fig 5). More-over, our procedure of distraction is reliable for obtaining

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Fig 10. Posttreatment cephalometric tracing. Fig 11. Superimposed tracings.

Fig 12. Estimation of facial symmetry.

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an ideal dental arch because the dentist can control theamount of movement precisely by giving instructionsto the patient to activate the distractor manually. Thisis a benefit for both clinicians and patients because thetreatment results are more reliable than with osteotomytechniques. Moreover, the distractor can maintain the

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transverse width as a retainer after activation by securingthe screw hole rigidly during the consolidation period of2months. There are possible complaints from the patientabout the corticotomy procedure, which must be donetwice in a 2-week interval. A 2-week (10-14 days) latencyperiod is required for tissue reconstruction and

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revascularization of that area.15 Therefore, patients mustreceive corticotomies twice within 2 weeks.

Postoperative skeletal stability is an important factorfor successful surgical orthodontic treatment. Andrewet al16 published a systematic review about stabilityand complications of mandibular advancement usingdistraction osteogenesis and sagittal split ramus osteot-omy. They found that both techniques have similar riskfactors for skeletal relapse. Harada et al17 reported thatmost relapse occurs within 6 months postoperatively.Kumar et al18 also reported the outcomes of 1-yearfollow-ups after surgery and showed excellent stability.Transverse widths at the maxillary premolars and firstmolars were nearly stable over the 2-year postoperativeinterval in our patient, and her overall long-term stabil-ity showed excellent results.

CONCLUSIONS

Our procedure is considered to have fewer compli-cations compared with other treatment plans. In addi-tion, the device is easy to manipulate, the techniqueis simple, and the surgical invasion is minimal to thepatient.

The strategy of using corticotomy and distractionosteogenesis to incline teeth and the accompanyingalveolar bone in 1 piece with a distractor is an effectiveand efficient treatment for the correction of an asym-metric maxillary dental arch.

REFERENCES

1. Barder AF, Sims MR. Rapid maxillary expansion and external rootresorption in man: a scanning slectron microscope study. Am JOrthod 1981;79:630-52.

2. Carmen M, Marcella P, Giuseppe C, Roberto A. Periodontal evalu-ation in patients undergoingmaxillary expansion. J Craniofac Surg2000;11:491-4.

3. Brezniak N, Wasserstein A. Root resorption after orthodontic treat-ment: part 2. Literature review. Am J Orthod Dentofacial Orthop1993;103:138-46.

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4. Harzer W, Schneider M, Gedrange T. Rapid maxillary expansionwith palatal anchorage of the hyrax expansion screw—pilot studywith case presentation. J Orofac Orthop 2004;65:419-24.

5. Javad HM, Farzan G, Behnam M. Numerical simulation of ortho-dontic bone remodeling. Orthod Waves 2009;68:64-71.

6. Huiskes R, Weinans H, Grootenboer HJ, Dalstra M, Fudala B,Slooff TJ. Adaptive bone-remodeling theory applied toprosthetic-design analysis. J Biomech 1987;20:1135-50.

7. Kale S, Kocadereli I, Atilla P, Asan E. Comparison of the effects of1,25 dihydroxycholecalciferol and prostaglandin E2 on orthodon-tic tooth movement. Am J Orthod Dentofacial Orthop 2004;125:607-14.

8. Verna C, Dalstra M, Melsen B. The rate and the type of orthodontictooth movement is influenced by bone turnover in a rat model. EurJ Orthod 2000;22:343-52.

9. Collins MK, Sinclair PM. The local use of vitamin D to increase therate of orthodontic tooth movement. Am J Orthod DentofacialOrthop 1998;94:278-84.

10. Landes CL, Laudemann K, Petruchin O, Mack MG, Kopp S,Ludwig B, et al. Comparison of bipartite versus tripartite osteot-omy for maxillary transversal expansion using 3-dimentional pre-operative and postexpansion computed tomography data. J OralMaxillofac Surg 2009;67:2287-301.

11. Bell WH, Dann JJ. Correction of dentofacial deformities by surgeryin the anterior part of the jaws. Am J Orthod 1973;64:162-87.

12. Converse JM,Horowitz SL. The surgical-orthodontic approach to thetreatment of dentofacial deformities. Am J Orthod 1969;55:217-43.

13. Proffit WR, White RP. Combined orthodontic and surgical man-agement of maxillary protrusion in adults. Am J Orthod 1973;64:368-83.

14. K€ole H. Surgical operations on the alveolar ridge to correct occlusalabnormalities. Oral Surg 1959;12:277-88.

15. Werner S, Grose R. Regulation of wound healing by growth factorsand cytokines. Physiol Rev 2003;83:835-70.

16. Andrew OW, Lim KC. Skeletal stability and complications of bilat-eral sagittal split osteotomies and mandibular distraction osteo-genesis: an evidence-based review. J Oral Maxillofac Surg 2009;67:2344-53.

17. Harada K, Sato M, Omura K. Long-term maxillomandibular skele-tal and dental changes in children with cleft lip and palate aftermaxillary distraction. Oral Surg Oral Med Oral Pathol Oral RadiolEndod 2006;102:292-9.

18. Kumar A, Gabbay JS, Nikjoo R, Heller JB, O'Hara CM, Sisodia M,et al. Improved outcomes in cleft patients with severe maxillarydeficiency after Le Fort I internal distraction. Plast Reconstr Surg2006;117:1499-509.

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