CASE REPORT

Distalization of the mandibular dentitionof an adult with a skeletal Class III malocclusion

Haikun Hu,a Jianwei Chen,a Jing Guo,b Fan Li,a Zeping Liu,a Shushu He,a and Shujuan Zouc

Chengdu, China, and Amsterdam, The Netherlands

aPhDtics, WbPostfor DUnivecProfeWestThe aucts oReprinmentSectioyahooSubm0889-Copyrhttp:/

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This case report describes the orthodontic treatment of an 18-year-old woman with a skeletal Class III malocclu-sion and a midline deviation. The treatment plan consisted of distalizing the mandibular dentition asymmetricallyand producing space for retraction of the mandibular anterior teeth. Short Class III elastics, an open-coil spring,and themulitloop edgewise archwire technique were used, combining the entire maxillary dentition as integratedanchorage. The active treatment period was 26 months. Normal overbite and overjet were obtained, and facialbalance was improved. (Am J Orthod Dentofacial Orthop 2012;142:854-62)

Askeletal Class III malocclusion is a commonorthodontic problem, with a prevalence of8% to 22% of all orthodontic patients.1 For

an adult patient with no potential for growth, treat-ment approaches depend on the growth, severity ofthe skeletal discrepancy, facial profile, and the patient’sdesires.2 Generally, this malocclusion can be correctedby camouflage orthodontic treatment or orthodontictreatment combined with orthognathic surgery. Insome borderline cases, the patient’s opinion of thesoft-tissue profile plays a decisive role in treatmentplanning.3 For patients with an acceptable facial pro-file, camouflage treatment is the best choice, and var-ious methods have been used, including multibracketswith Class III elastics with or without tooth extrac-tions.4-6 Class III elastics often result in unexpectedrotation of the mandible and proclination of themaxillary incisors and extrusion of the molars.7 Thiscan cause an esthetic problem and instability, espe-cially in long-faced adults.

Therefore, microscrew and miniplate implantanchorage for distalization of the mandibular posterior

student, State Key Laboratory of Oral Diseases, Department of Orthodon-est China School of Stomatology, Sichuan University, Chengdu, China.

doctoral research fellow, Department of Oral Cell Biology, Academic Centreentistry Amsterdam (ACTA), Research Institute MOVE, VU University andrsity of Amsterdam, Amsterdam, The Netherlands.ssor, State Key Laboratory of Oral Diseases, Department of Orthodontics,China School of Stomatology, Sichuan University, Chengdu, China.uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Shujuan Zou, State Key Laboratory of Oral Diseases, Depart-of Orthodontics, West China School of Stomatology, Sichuan University, 14n 3 Ren Min Nan Lu, 610041 Chengdu, China; e-mail, shujuanzou@.com.cn.itted, revised and accepted, March 2011.5406/$36.00ight � 2012 by the American Association of Orthodontists./dx.doi.org/10.1016/j.ajodo.2011.03.030

teeth was introduced.8 However, some patients do notreadily accept this invasive approach because of thehigh cost and the risk of various complications, includ-ing injury to adjacent structures, inflammation, infec-tion around the implant site, failure, and fracture.9 Thegoal of providing these patients a satisfactory facial pro-file and a stable occlusion without microimplantanchorage is worth consideration.

The purpose of this case report is to present an adultwith a skeletal Class III malocclusion and a midline devi-ation treated with fixed orthodontic appliances, shortintermaxillary elastics, and an open-coil spring tomove the mandibular molars distally. This treatmentproduced a satisfactory facial profile and a stable occlu-sion.

DIAGNOSIS AND ETIOLOGY

An 18-year-old woman was referred to Departmentof Orthodontics, West China School of Stomatology,Chengdu, China, for treatment, with the chief com-plaint of dissatisfaction with her dental alignment.Cephalometric and panoramic radiographs, extraoraland intraoral photographs, and dental casts wereobtained.

The extraoral examination (Fig 1) showed that shehad a relative long lower face and an acceptable profilewith a slightly protrusive chin. The intraoral examina-tion (Fig 1) showed a complete Class III molar relation-ship on the left and a mild Class III malocclusion on theright, and Class III canine relationships bilaterally.There was an edge-to-edge anterior occlusion, andthe maxillary left second molar was positioned buccallyand overerupted. Mild crowding of 2.5 mm was presentin the mandibular anterior region, and a little crowdingwas found in the maxillary dentition. The maxillary

Fig 1. Pretreatment facial and intraoral photographs.

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midline was coincident with the facial midline, whereasthe mandibular midline was deviated 2 mm to the rightside (Fig 2). The functional examination showed noabnormal features, and there were no symptoms oftemporomandibular disorder. The patient was ingood general health with no history of major systemicdiseases.

The lateral cephalometric analysis (Fig 3; Table) indi-cated a skeletal Class III jaw relationship (ANB, –3.4�)with mandibular protrusion (SNB, 85.2�). The mandibu-lar plane angle (MP-SN, 36.0�) had a mild verticalgrowth pattern. The maxillary incisors were labially pro-clined (U1-NA, 32.0�), and a lingual inclination wasobserved at the mandibular anterior teeth (IMPA,86.8�). The panoramic radiograph showed that all teethwere present except for the mandibular left third molar,and the maxillary and mandibular right third molarswere impacted.

American Journal of Orthodontics and Dentofacial Orthoped

The patient was diagnosed with a dental Class III ma-locclusion, a mandibular midline deviation, mandibularincisor crowding, and a skeletal Class III jaw relationshipcaused by the mandibular protrusion.

TREATMENT OBJECTIVES

The treatment objectives were to (1) correct the ante-rior edge-to-edge occlusion and establish a normal incisorrelationship, (2) achieve Class I molar and canine relation-ships by uprighting and distalizing the mandibular poste-rior teeth, (3) resolve the crowding in themandibular arch,(4) correct the mandibular midline deviation, and (5)maintain the straight pretreatment facial profile.

TREATMENT ALTERNATIVES

Three treatment options were considered and pre-sented to the patient. The first alternative consisted of

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Fig 2. Pretreatment dental casts.

Fig 3. Pretreatment radiographs: A, pretreatment pano-ramic radiograph; B, pretreatment cephalograph.

Table. Cephalometric measurements

Measurement Normal mean SD Pretreatment PosttreatmentSNA (�) 81.69 2.54 81.8 83.2SNB (�) 78.94 2.19 85.2 84.1ANB (�) 2.75 1.16 �3.4 �0.9MP-SN (�) 32.85 4.21 36.0 37.6UI-LI (�) 123.22 6.18 132.4 120.8U1 to NA (mm) 5.56 3.6 9.9 9.1U1 to NA (�) 23.26 6.17 32.0 36.4L1 to NB (mm) 5.76 2.29 5.0 5.5L1 to NB (�) 27.38 4.74 28.0 23.7FMIA (�) 54.6 6.5 64.8 68.5IMPA (�) 96.3 5.8 86.8 82.0UL-EP (mm) �0.46 1.92 �2.6 �1.2LL-EP (mm) 1.31 1.92 0.1 0.7

856 Hu et al

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combined surgical and orthodontic treatment witha mandibular setback. This proposal would be the bestway to modify the skeletal pattern and produce a dra-matic facial profile change. The second consisted ofcamouflage orthodontic treatment with extraction ofthe mandibular left first premolar. This would be a rela-tively simple and stable way to resolve the anterior cross-bite, but there would be no contact between the

Journal of Orthodontics and Dentofacial Orthopedics

Fig 4. Progress photographs: mandibular left second molar distalized by open-coil spring and shortClass III elastics.

Fig 5. Progress photographs: multiloop edgewise archwire of 0.019 3 0.025-in stainless steel wasplaced in the mandibular arch with short Class III elastics.

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maxillary left second molar and the opposing tooth. Theother treatment alternative was a nonextraction camou-flage orthodontic approach with distalization of themandibular dentition. If the mandibular left second mo-lar could not be distalized effectively because of themaxillary left second molar, the latter tooth would be ex-tracted and replaced by the third molar. This would solvethe problems of the posterior malposition and the molarrelationship at the same time.

The patient refused the orthodontic-surgical treat-ment because she did not think that the esthetic

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improvement with surgery would be worth the risk andcost. She chose the third plan of distalizing the mandib-ular dentition because she cared about her dental andfacial midlines and wanted to obtain complete functionof her posterior teeth.

In most skeletal Class III cases, intraoral or extraoralanchorage is required to retract the mandibular dentalarch. There were 2 anchorage alternatives for thispatient to choose from. One was distalizing the mandib-ular posterior dentition with a microimplant combinedwith intra-arch elastics. The other was interarch elastics

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Fig 6. Posttreatment facial and intraoral photographs.

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with the whole maxillary dentition as anchorage to re-tract the mandibular arch, with an open-coil spring tomove the mandibular left molars distally. The patientwas concerned about the invasive approach with poten-tial complications and additional costs and refused theplacement of a microimplant.

TREATMENT PROGRESS

The treatment objectives and alternatives wereexplained to the patient, and informed consent wasobtained. A 0.022 3 0.028-in preadjusted edgewiseappliance was used. At the first session, banding andbonding were performed from first molar to first molarin themaxillary arch. A coordinated archwire for themax-illary dentition of 0.018 3 0.025-in stainless steel wasplaced with a boot loop as a hook for short Class III elas-tics (3/16 in, 3.5 oz). A sectional archwire (0.018 3

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0.025-in stainless steel) was used from the first premolarto the second molar on the right side of mandibular arch.In the left region of mandible, only the first premolar andthe secondmolarwere included, betweenwhich an open-coil spring was placed to move the second molar distallyon an 0.018 3 0.025-in stainless steel wire.

After 2 months of treatment, the mandibular left sec-ond molar was distalized by 2 mm but still required fur-ther movement. At the same time, distal movement ofthe mandibular posterior teeth was severely hinderedby the maxillary left second molar because of its buccalmalposition and overeruption. The patient agreed withthe plan to extract the maxillary left second molar. Amultiloop edgewise archwire of 0.0193 0.025-in stain-less steel was then placed in the maxillary arch with con-tinuous use of the short Class III elastics.

After 5 months of Class III elastics, the anterior cross-bite was corrected. There was a space of 4 mm between

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Fig 7. Posttreatment dental casts.

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the mandibular left first and second molars (Fig 4). Dis-talization of the mandibular left first molar was startedwith an open-coil spring between the first premolarand the first molar.

At the seventh month of treatment, the mandibularleft first molar moved to the mesial surface of the secondmolar, and there was distal drift of the second premolar.Subsequently, the brackets were bonded on the remain-ing teeth in the mandibular arch. Serial archwires wereplaced, from a 0.014-in nickel-titanium archwire to an0.018 3 0.025-in stainless steel wire to level and alignthe maxillary and mandibular dentitions.

During these phases, sequential distal movements ofthe mandibular left second premolar, first premolar, andcanine were performed with elastomeric chains. To cor-rect the mild mesial molar relationship, a multiloopedgewise archwire of 0.019 3 0.025-in stainless steelwas placed in the mandibular arch with short Class IIIelastics in the anterior region (Fig 5). The lingual crowntorque and labial crown torque were accentuated for themaxillary and mandibular incisors, respectively, againstthe elastic forces.

After correction of the anterior edge-to-edge occlu-sion and creation of a Class I molar and canine occlusion,detailing and finishing were undertaken. The total activetreatment time was 26 months. Patient compliance was

American Journal of Orthodontics and Dentofacial Orthoped

good throughout treatment. After treatment, maxillaryand mandibular circumferential retainers were madeand used full time for 1 year and then at night only.

TREATMENT RESULTS

The patient was pleased with the treatment results.The posttreatment extraoral photographs (Fig 6)showed that her facial profile remained straight, andher protrusive chin had been retracted slightly. The post-treatment intraoral photographs (Fig 6) and dental casts(Fig 7) demonstrated satisfactory dental alignment, ClassI canine and molar relationships, and normal overjet andoverbite. The dental midline was corrected and broughtto coincide with the facial midline. The mandibular den-tition was notably distalized by 5 mm on the left and2 mm on the right (Fig 7). The maxillary left third molarwas moved parallel to the second molar extraction spaceand had good occlusion with the mandibular molar.

The superimposed pretreatment and posttreatmentcephalometric tracings (Figs 8 and 9; Table) accordingto the anterior cranial base showed that the ANB angleincreased from –3.4� to –0.9�. The maxillary incisorsshowed a slight labial proclination, and the mandibularincisors were uprighted and retracted. The mandibularplane angle changed little in spite of the significant

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Fig 8. Posttreatment radiographs: A, posttreatment pan-oramic radiograph; B, posttreatment cephalograph.

Fig 9. Superimpositions of pretreatment (black line) andposttreatment (red line) cephalometric tracings.

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mandibular molar distalization. Mild extrusion of themaxillary molars resulted in counterclockwise rotationof the occlusal plane but caused little backward rotationof the mandible and no remarkable negative changes inthe facial height or the soft-tissue profile.

The patient was asked to wear the removable retainerall day for the first year. One year later, the follow-upexamination (Fig 10) showed a well-proportioned soft-tissue profile. The occlusion remained stable, with normaloverjet and overbite. There were no signs or symptoms ofany temporomandibular disorder during the treatmentand retention periods. The retainer was worn at nightonly for another year.

DISCUSSION

Whether to treat an adult with a skeletal Class III mal-occlusion by orthognathic surgery or orthodontic cam-ouflage treatment is still controversial. Treatmentapproaches depend on different patterns of growth,severity of the skeletal discrepancy, facial profile, andpatient requirements.2 For borderline cases, the soft-tissue profile plays an important part in treatment plan-ning.3 With mild crowding and an acceptable straightprofile, our patient chose camouflage treatment. Aftertreatment, her facial profile was still straight, and her

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protrusive chin had been retracted slightly as expected,producing a more balanced and harmonious facialprofile.

The orthodontic camouflage options for adults witha skeletal Class III malocclusion include various extrac-tion patterns. Mandibular incisor extraction is some-times indicated in moderate Class III malocclusionswith an anterior crossbite or an edge-to-edge incisor re-lationship.10 It depends on the severity of anteriorcrowding, Bolton analysis, and amounts of overbiteand overjet. In this patient, it would have caused a man-dibular midline deviation and an excessive overjet ofthe anterior dentition. Another treatment alternative ofextracting the mandibular left first premolar withoutmoving the mandibular molars distally might have pro-vided a normal anterior relationship, but the maxillaryleft second molar would not have occlusal contactwith the opposing tooth.

It has been reported that anteroposterior intermaxil-lary elastics can produce significant adverse vertical ef-fects.11 However, these can be prevented by properdesign and manipulation. In this patient, throughoutthe distalization phrase, the entire maxillary dentitionwas supported with an 0.018 3 0.025-in stainless wireas integrated anchorage against the Class III elastic

Journal of Orthodontics and Dentofacial Orthopedics

Fig 10. Facial and intraoral photographs 1 year after treatment.

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forces. In the maxillary arch, a coordinated archwire wasplaced with stop loops to maintain the transverse dimen-sion. Short Class III elastics were used from boot loopsbetween the maxillary first and second premolars tothe hooks mesial to the mandibular first premolars, tocounteract the adverse labial inclination forces on themandibular incisors from the open-coil spring. Com-pared with long Class III elastics, the force is closer tothe center of resistance of both the maxilla and the max-illary arch, partly preventing forward movement of themaxillary dentition.

In previous studies, distalization of the entire man-dibular dentition was accompanied by a slight mandib-ular posterior tooth extrusion and an increase in themandibular plane angle; these movements are not suit-able for patients with long faces.12 The multiloop edge-wise archwire technique for Class III malocclusions hasmany loops to provide second-order control of the pos-terior teeth, permit individual tooth movement, and

American Journal of Orthodontics and Dentofacial Orthoped

transmit the force generated by the intermaxillary elas-tics throughout the entire arch.13 In this patient, themultiloop edgewise archwires (0.019 3 0.025-in stain-less steel) were placed in the maxillary and mandibulararches with tip-back mechanics, so that efficientuprighting and intrusion of the mandibular molars, cor-rection of the midline deviation, and relief of anteriorcrowding could be achieved. With the coordination ofthe maxillary and mandibular arches, the patient hadonly counterclockwise rotation of the occlusal planeinstead of significant backward and downward mandib-ular rotation. As a result, the mandibular plane anglechanged little, as expected; this was appropriate for a pa-tient with a vertical growth pattern.

The satisfactory occlusion and harmonious appear-ance are due to appropriate dentoalveolar compensationaccompanied by maxillary incisor proclination andbodily retrusion of the mandibular incisor. It was be-lieved that the incisor movement was partly controlled

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862 Hu et al

by the bracket system and mechanics.14 As we know,Class III elastics have a labial proclination tendency forthe maxillary incisors and a lingual retroclination ten-dency for the mandibular incisors. To counteract theadverse forces of Class III elastics, resistant torques areneeded. Therefore, the lingual crown torque and thelabial crown torque were accentuated for the maxillaryand mandibular incisors, respectively, to counteract theexcessive elastic forces.

Microimplant anchorage has some advantages. It canbe placed either between the first and second molars orbetween the second premolar and the first molar in themandibular arch.15 With intra-arch elastics, the entiremandibular dentition would be distalized with no move-ment of the maxillary dentition. However, because of thehigh cost and complications of surgery, including in-flammation and infection around the implant site, injuryto adjacent structures, failure, and fracture, somepatients do not accept this invasive approach.9 For thesepatients, the maxillary coordinated archwire can be com-bined with various anchorage alternatives, includinga palatal bar or headgear, to maintain the transverseand vertical relationships and prevent the adverse effectsof Class III elastics. Nomatter which anchorage pattern isused, the magnitude, direction, and point of applicationof the force should be carefully monitored.

The relationship between intermaxillary elastics andtemporomandibular disorders still lacks a clear consen-sus. Etiologic factors that might cause upward and back-ward pressures on the mandible should be minimized asmuch as possible.16 Some authors believe that a posteriorforce on the condyle will induce anterior disc displace-ment.17 Others have demonstrated that temporoman-dibular disorder signs and symptoms are changing,inconsistent, and ephemeral in many orthodontic pa-tients, regardless of the different treatment mechanicsincluding headgear, Class II or Class III elastics, extrac-tion, and nonextraction.18 Further studies are indicatedto document that traditional orthodontic treatments donot increase the prevalence of temporomandibulardisorders.19 In this patient, we used short Class III elasticsas a supplementary means to correct the Class III maloc-clusion and to prevent an undesirable labial inclinationof the mandibular anterior teeth. With light and contin-uous forces, the patient showed no discomfort of thetemporomandibular joint and no pain on palpationthroughout the treatment and retention periods.

CONCLUSIONS

This case report demonstrates that fixed orthodonticappliances with intermaxillary elastics, open-coilsprings, and multiloop edgewise archwires can be an

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effective method to move the mandibular dentition dis-tally to correct a Class III malocclusion and a midlinedeviation for an adult.

REFERENCES

1. Egermark-Eriksson I, Carlsson GE, Magnusson T, Thilander B.A longitudinal study on malocclusion in relation to signs andsymptoms of cranio-mandibular disorders in children and adoles-cents. Eur J Orthod 1990;12:399-407.

2. Proffit WR, Fields HW, Sarver DM. Contemporary orthodontics.4th ed. St Louis: Mosby-Year Book; 2007. p. 689-93.

3. Kerr WJS. Changes in soft tissue profile during the treatment ofClass III malocclusion. Br J Orthod 1987;14:243-9.

4. Lin JX, Gu Y. Preliminary investigation of nonsurgical treatment ofsevere skeletal Class III malocclusion in the permanent dentition.Angle Orthod 2003;73:401-10.

5. Moullas AT, Palomo JM, Gass JR, Amberman BD, White J. Nonsur-gical treatment of a patient with a Class III malocclusion. Am JOrthod Dentofacial Orthop 2006;129(Suppl):S111-8.

6. Janson G, de Souza JE, Alves FA, Andrade P Jr, Nakamura A, deFreitas MR. Extreme dentoalveolar compensation in the treatmentof Class III malocclusion. Am J Orthod Dentofacial Orthop 2005;128:787-94.

7. Proffit WR. Interarch elastics: their place in modern orthodon-tics. In: Hosl E, Baldauf A, editors. Mechanical and biologicalbasics in orthodontic therapy. Heidelberg, Germany: HuthigBuchverlag; 1991. p. 173-8.

8. Park HS, Lee SK, Kwon OW. Group distal movement of teeth usingmicroscrew implant anchorage. Angle Orthod 2005;75:602-9.

9. Odman J, Lekholm U, Jemt T. Osseointegrated implants as ortho-dontic anchorage in the treatment of partially edentulous adultpatients. Eur J Orthod 1994;16:187-201.

10. Canut JA. Mandibular incisor extraction: indication and long-termevaluation. Eur J Orthod 1996;18:485-9.

11. Miyajima K, Iizuka T. Treatment mechanics in Class III open bitemalocclusion with tip edge technique. Am J Orthod DentofacialOrthop 1996;110:1-7.

12. de Alba y Levy JA, Caputo AA, Chaconas SJ. Effects of orthodonticintermaxillary Class III mechanics on craniofacial structures. Parts Iand II. Angle Orthod 1979;49:21-36.

13. Kim YH, Han UK, Lim DD, Serraon ML. Stability of anterior open-bite correction with multiloop edgewise archwire therapy: a ceph-alometric follow-up study. Am J Orthod Dentofacial Orthop 2000;118:43-54.

14. Goldin B. Labial root torque: effect on the maxilla and incisor rootapex. Am J Orthod Dentofacial Orthop 1989;95:208-19.

15. Costa A, Raffaini M, Melsen B. Miniscrews as orthodontic anchor-age: a preliminary report. Int J Adult Orthod Orthog Surg 1998;13:201-9.

16. Wyatt WE. Preventing adverse effects on the temporomandibularjoint through orthodontic treatment. Am J Orthod Dentofacial Or-thop 1987;91:493-9.

17. Farrar WB, McCarty WL. A clinical outline of temporomandibularjoint diagnosis and treatment. Montgomery, Ala: Walker Printing;1983. p. 84-5.

18. Owen A. Unexpected temporomandibular joint findings duringfixed appliance therapy. Am J Orthod Dentofacial Orthop 1998;113:625-31.

19. Kim MR, Graber TM. Orthodontics and temporomandibular disor-der: a meta-analysis. Am J Orthod Dentofacial Orthop 2002;121:438-46.

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