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Anterior Crossbite Correction with a Series of Clear Removable Appliances: A Case ReportJAE HYUN PARK, DMD, MSD, MS, PhD* TAE WEON KIM, DDS, MSD, PhD ABSTRACT The Clear Aligner can be used to correct tooth movement without involving extraction, surgery, and other adjunct orthopedic appliances. The Clear Aligner is a procedure that can be performed by either an orthodontist or a general dentist without computer simulation/ calculation. Since the Clear Aligner is fabricated from the stone model for new appliance at each or every other appointment, it is readily available to change the treatment sequence throughout the course of the treatment. The patient can receive any necessary dental proce- dures with ease during the course of the treatment. The treatment can also be easily resumed even if the patient has not worn the aligners for a period of time. The purpose of this article is to report dental anterior crossbite correction with a series of Clear Aligners. The Clear Aligner could be used as an alternative in appropriate cases for those who are reluctant with conventional appliances. CLINICAL SIGNIFICANCE The Clear Aligner, a clear removable orthodontic device, can perform tooth movement for the following: crowding resolution, space closure, arch expansion or constriction, anterior, or pos- terior crossbite correction, space maintenance or regaining, and other prosthodontic treatments combined with orthodontic treatment. 1–3 This article illustrates an example of its use. (J Esthet Restor Dent 21:149–160, 2009) INTRODUCTION A nterior crossbites are not esthetically pleasing. Until recently, the process of straighten- ing the teeth typically has involved appliances involving bands, brack- ets, and wires that can be difficult to clean. The desire for a cosmetic solution to misaligned teeth has led to an increase in the number of patients seeking veneers, crowns, and other laboratory-fabricated cosmetic restorations. Dental ante- rior crossbites are dental malocclu- sions resulting from abnormal axial inclinations of maxillary anterior teeth, whereas skeletal anterior crossbites are usually part of a skeletal problem such as man- dibular prognathism and midface deficiency. 4 The correction of dental anterior crossbites is a common orthodontic treatment that may be performed with a removable or fixed appliance or a combination of both. This treat- ment has been recommended to prevent abnormal enamel abra- sions, fractures of anterior teeth, periodontal pathosis, and to produce a more esthetic dentofacial complex and a better occlusion. 5–7 *Director, Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, Mesa, AZ, USA President of Korean Society of Lingual Orthodontics, Private Practice of Orthodontics, Seoul, South Korea © 2009, COPYRIGHT THE AUTHORS JOURNAL COMPILATION © 2009, WILEY PERIODICALS, INC. DOI 10.1111/j.1708-8240.2009.00257.x VOLUME 21, NUMBER 3, 2009 149
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Anterior Crossbite Correction with a Series of ClearRemovable Appliances: A Case Reportjerd_257 149..159

JAE HYUN PARK, DMD, MSD, MS, PhD*

TAE WEON KIM, DDS, MSD, PhD†

ABSTRACTThe Clear Aligner can be used to correct tooth movement without involving extraction,surgery, and other adjunct orthopedic appliances. The Clear Aligner is a procedure that can beperformed by either an orthodontist or a general dentist without computer simulation/calculation. Since the Clear Aligner is fabricated from the stone model for new appliance ateach or every other appointment, it is readily available to change the treatment sequencethroughout the course of the treatment. The patient can receive any necessary dental proce-dures with ease during the course of the treatment. The treatment can also be easily resumedeven if the patient has not worn the aligners for a period of time. The purpose of this article isto report dental anterior crossbite correction with a series of Clear Aligners. The Clear Alignercould be used as an alternative in appropriate cases for those who are reluctant withconventional appliances.

CLINICAL SIGNIFICANCEThe Clear Aligner, a clear removable orthodontic device, can perform tooth movement for thefollowing: crowding resolution, space closure, arch expansion or constriction, anterior, or pos-terior crossbite correction, space maintenance or regaining, and other prosthodontic treatmentscombined with orthodontic treatment.1–3 This article illustrates an example of its use.

(J Esthet Restor Dent 21:149–160, 2009)

I N T R O D U C T I O N

Anterior crossbites are notesthetically pleasing. Until

recently, the process of straighten-ing the teeth typically has involvedappliances involving bands, brack-ets, and wires that can be difficultto clean. The desire for a cosmeticsolution to misaligned teeth has ledto an increase in the number of

patients seeking veneers, crowns,and other laboratory-fabricatedcosmetic restorations. Dental ante-rior crossbites are dental malocclu-sions resulting from abnormalaxial inclinations of maxillaryanterior teeth, whereas skeletalanterior crossbites are usually partof a skeletal problem such as man-dibular prognathism and midfacedeficiency.4 The correction of

dental anterior crossbites is acommon orthodontic treatmentthat may be performed with aremovable or fixed appliance or acombination of both. This treat-ment has been recommended toprevent abnormal enamel abra-sions, fractures of anterior teeth,periodontal pathosis, and toproduce a more esthetic dentofacialcomplex and a better occlusion.5–7

*Director, Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, Mesa, AZ, USA†President of Korean Society of Lingual Orthodontics, Private Practice of Orthodontics, Seoul, South Korea

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Furthermore, habitual mandibularmalpositioning and inappropriatepattern of jaw musculature relatedto crossbite may adversely affectmaxillary and mandibular growthand potentiate temporomandibularjoint abnormalities.8

For esthetics, clear brackets may beplaced, however, they can be irri-tating to the cheeks and gumsbecause they are large and bulky.Lingual braces are a great optionfor those who want straight teethand a beautiful smile withoutshowing any braces.9,10 While thelingual clinical techniques havebeen developed, lingual treatmentmay not be cost effective due toincreased chair time. Invisalign(Align Technology, Santa Clara,CA, USA) was developed for thebenefit of cleaning of the teetheasily and going about normal lifewithout interruption.11–14 Theseappliances are particularly popularamong adults who want tostraighten their teeth without theunflattering look of traditionalmetal braces, which are commonlyworn by children and adolescents.

The Clear Aligner can move theteeth easily without braces. It isdifferent from Invisalign, whichprovides serial aligners from oneimpression.11–14 Rather than justdelivering the aligners, the clinicianshould be the pilot of the treat-ment. The main reason for the fab-rication of the Clear Aligner every

3 to 6 weeks is that the cliniciancan control tooth movement moreprecisely. The Clear Aligner is anefficient orthodontic appliance pro-duced periodically.12 It can beeasily fabricated by either an orth-odontist or a general dentist intheir own labs. In order to fabri-cate a Clear Aligner, impressionsare taken for the working cast thatare used with two or three differ-ent plastic sheets (Duran, Scheu-dental, Iserlohn, Germany) and apressure molding machine (Biostar,Scheu-dental) or a vacuum machine(Dentsply Raintree Essix, Metairie,LA, USA).1–3 Different plastic sheetsare thermoformed on the setupmodel made for tooth movementusing a vacuum former. The toothmovement is very efficient, and thepatient feels comfortable.

C A S E R E P O RT

A 28-year-old Korean female wasreferred to the orthodontist forevaluation of anterior crossbite.Her chief complaint was the unes-thetic appearance of her upperanterior teeth, which were behindthe lower anterior teeth and shewanted esthetic treatment with acomfortable appliance. There wereno significant findings in hermedical and dental histories. Thepatient presented a mesofacial,symmetrical face, and a straightprofile (Figure 1). She showed mod-erate crowding on the upper archwith an anterior crossbite and mildspacing on the lower arch with

lingually tilted lower right and leftcanines. She had a Class I molarrelationship on both sides with-1 mm overjet and 50% overbite.On smiling, the patient showedexcessive gingiva on the maxillarycentral incisors. Although the max-illary dental midline was coincidentwith the facial midline, the man-dibular dental midline was deviated1 mm to the right when the man-dible was guided in centric relation,and the maxillary central incisorsshowed fractures on incisal edges incentric relation (Figure 2). The pan-oramic radiograph demonstratedno evidence of bone or dentalpathology (Figure 3A). Cephalom-etric analysis indicated a skeletalClass III (ANB = -2) with hypodi-vergent growth pattern (SN-GoGn:27). The maxillary incisors wereretroclined (U1 to SN: 95) and themandibular incisors showed procli-nation (IMPA: 109) (Figure 3B).The treatment objectives for thispatient were to correct the anteriorcrossbite, to establish normal over-bite and overjet, to align the ante-rior teeth for ideal inclination, toobtain a stable occlusal relation-ship, and to improve the patient’sfacial and dental esthetics by resolv-ing an anterior gummy smile.Before orthodontic treatment, shehad a consultation with a periodon-tist and a general dentist for gingi-vectomy and restoration of uppercentral incisors. In order to correctanterior crossbite and to align themaxillary anterior teeth, oblique

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lateral and anterior-posterior (A-P)expansion was performed usingthree aligners (Figures 4–6). Twoaligners were used to align thelower arch (Figure 7). Because thepatient had only mild spacing onthe lower arch in order to uprightthe lower incisors, approximately3 mm of interproximal reduction(IPR) was achieved in the loweranterior dentition.

When fabricating the setup modelfor a Clear Aligner, the informa-tion of tooth angulations (e.g.,upper incisor to SN and IMPA)can be converted to the setupmodel using the Clear Alignermodel checker (IV-Tech, Seoul,South Korea). Consequently, it is

possible to determine ideal torqueand angulation of anterior denti-tion during setup model fabrication(Figure 8A).1–3 The Clear Aligneralso uses an aligner aid program(AAP) (IV-Tech) to fabricate asetup model. The AAP combinedwith a 2D digital camera could beused to accurately measure themovement. Before fabricating thesetup model, the initial workingcast photo is taken using a digitalcamera. After the target tooth ismoved to the desired position, it isfixed by the baseplate wax or BlueBlokker (Scheu-dental) and adigital photo is retaken. Setupchanges can be exactly measuredand verified by overlaying digitalphotos. It can control tooth

movements every 0.1 mm. Thiscomputer-compatible programmeasures distance and angles ofteeth movements on setup models(Figure 8B).1–3

After jumping the bite, the patientwas referred to a periodontist for agingivectomy procedure to level thegingival heights on the maxillarycentral incisors (Figure 9). Theanterior crossbite was correctedafter orthodontic treatment. Thepatient was referred to the generaldentist for veneer restorations onthe maxillary central incisors.Acceptable overjet and overbitewere established after esthetic res-torations were finished (Figure 10).The patient completed treatment

Figure 1. Initial facial photographs.

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with the same facial profile as pre-treatment (Figure 11). The pan-oramic radiograph showedexcellent root parallelism(Figure 12A). Cephalometric analy-sis revealed a skeletal Class I(ANB = 0) with hypodivergentgrowth pattern (SN-GoGn: 27). Themaxillary incisors (U1 to SN: 110)showed decent inclination and themandibular incisors (IMPA: 100)

showed close to normal inclinationconsidering her flat mandibularplane (Figure 12B). Clinical exami-nation of the mandibular positiondid not show that the mandibleshifted backwards, and there wasno evidence of a centric relation-centric occlusion shift. The totaltreatment time was approximately6 months; 5 months for orthodon-tic treatment time including

gingivectomy and 1 month forporcelain veneers on the maxillarycentral incisors. After the orthodon-tic treatment and esthetic work wasdone, the patient was given a newClear Aligner as a retainer.

D I S C U S S I O N

Anterior crossbite is defined as amalocclusion resulting from thelingual position of the maxillary

Figure 2. Initial intraoral photographs.

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anterior teeth in relationship withthe mandibular anterior teeth. Thecorrection of dental anterior cross-bite may involve lingual movementof a mandibular tooth, labialmovement of the maxillary tooth,or both. Differential diagnosis ofdental versus skeletal anteriorcrossbite is essential in the selec-tion of cases that can be treated.Skeletal correction requires compli-cated appliances, and the continu-ous abnormal jaw growth can leadto relapse. To differentiate dentalcrossbite from skeletal crossbite,

one should attempt to guide themandible in centric relation andevaluate the molar and incisor rela-tionship. Furthermore, the relativesize of the mandible shouldbe compared with the maxillausing model analysis along withcephaolmetric assessment.

In the absence of a family history ofClass III malocclusion, and uponmanipulation of the mandible, ifthe incisors obtain an end-to-endrelationship, it may indicate thepresence of a dental problem. If the

molars are in a Class I relationshipand the incisors at an end-to-endrelationship, a dental correction canbe undertaken. The Clear Alignerwas chosen for her treatmentbecause her crossbite was a dentalorigin and she wanted a clearremovable appliance. The patientshowed an improved overbite rela-tionship after the appliance wasremoved (Figure 9). Once positiveoverbite is achieved, relapse is rarein dental anterior crossbite; how-ever, adequate overbite depth to“hold” the correction is necessary.

A B Figure 3. Initial radiographic views: A, Panoramic view. B, Lateralcephalometric view.

A B C Figure 4. Diagrammatic representation of oblique lateral expansion (A) and A-P expansion (B). Two different plastic ClearAligners fabricated from the setup model (C).

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Figure 5. Oblique lateral and A-P expansion was performed on upper arch using Clear Aligners.

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An important factor to consider inorthodontic treatment is whetherto use a removable or a fixedappliance. Not only for oral

hygiene15,16 but also for estheticreasons,11–14 removable ClearAligner appliances have advan-tages. They reduce chair time

during treatment because they arefabricated in the laboratory. Inaddition, in orthodontic treatmentcombined with prosthodontic

A B C D

Figure 6. Intraoral photographs showing overjet and overbite changes before (A), during (B), after orthodontic treatmentwith gingivectomy (C), and veneer restorations (D) on maxillary central incisors.

A B C Figure 7. Intraoral photographs showing alignment of lower arch before (A) and after (C) treatment using Clear Aligners(B).

A B

Figure 8. A, The setup model is fabricated with torque on the upper archusing the Clear Aligner model checker. B, Aligner aid program (AAP)presenting the information of tooth movement. Pretreatment model isrepresented by the black lines and final setup model is represented by the redlines.

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treatment, after orthodontic treat-ment is completed, the last alignercould be used as a retainer untilprosthodontic restorations arecompleted. General dentists canalso perform restorative work withease since the patient does nothave braces. Teeth can be movedafter temporary or final restora-tions are finished as well.

A potential disadvantage of thistype of appliance is that it is highlydependent on patient compliance.14

The aligner should be worn at least17 hours per day including sleep-ing time,1–3 yet, current datasuggest that this rarely is anissue.13,14 There were no compli-ance issues with this patient andtreatment time appeared to be

consistent with what might beexpected with fixed appliances.The other significant weakness isthe aligner’s inability to move theroot apex, such as in torquing ortranslational movements. Tippingof teeth into the extraction space isnearly impossible to avoid, evenwith fixed appliances, and tippingis exaggerated in an adult patient.

Figure 9. Intraoral photographs after orthodontic treatment with gingivectomy on maxillary central incisors.

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A B

C D Figure 10. Intraoral frontal and smiling views before (A,C) and after (B,D)orthodontic treatment including esthetic work, gingivectomy and porcelainveneers on maxillary central incisors.

Figure 11. Final facial photographs.

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Complex attachment designs forteeth adjacent to the extraction sitehelp reduce tipping, but sectionalfixed appliances are necessary inalmost all such cases. During ortho-dontic treatment with ClearAligner, the attachments are some-times utilized, however, in this par-ticular case, the attachments werenot used. The Clear Aligner doesnot use attachments as oftenas Invisalign.1–3

Invisalign also uses the CT imagesof PVS impressions, which aretransferred to special softwarecalled “Treat” software. It has anumber of components thatperform different functions. Never-theless, it is not as accurate as theClear Aligner especially in finishingstages because it is provided byserial aligners.

This case demonstrates how theClear Aligners were used to treatanterior crossbite. The patient’sgingival health was maintainedthroughout the treatment period

and decalcification of the surfaceof the teeth was avoided. Thepatient did not notice any discom-fort during the course of thetreatment. The patient’s chiefconcern was addressed and treatedto her satisfaction. An estheticsmile was established, and themalocclusion was treated to astable result.

C O N C L U S I O N

Because the Clear Aligner is usedfor minor tooth movement, thetreatment plan is based onpatient’s chief complaints. If apatient wears the aligner for a rec-ommended period of time, thetooth movement is efficientbecause the aligner contacts thewhole tooth surface. Esthetics isexcellent with aligners because ofthe fact that they are hardlyvisible. This can be a definite psy-chological advantage to teenagersand adults alike. The Clear Alignercould be used as an effective alter-native in appropriate cases for

those who are reluctant to useconventional fixed appliances.

D I S C L O S U R E

The authors have no financialinterest in any of the companieswhose products are included inthis article.

R E F E R E N C E S

1. Kim TW, Park JH. An aesthetic ortho-dontic treatment option: fabrication andapplications. Dent Today 2008;27:132–5.

2. Kim TW. Clear aligner manual. Seoul,South Korea: Myungmun Publishing,Inc.; 2007:10–50.

3. Kim TW. Illustrated clear aligner fabrica-tion procedure. Seoul, South Korea:Myungmun Publishing, Inc.; 2007:38–79.

4. Moyers RE. Handbook of orthodontics.Chicago (IL): Yearbook Publishers Inc.;1973:564–77.

5. Lee BD. Correction of crossbite. DentClin North Am 1978;22:647–68.

6. Valentine F, Howitt JW. Implications ofearly anterior crossbite correction. J DentChild 1970;37:420–7.

7. Payne RC, Mueller BH, Thomas HF.Anterior crossbite in the primary denti-tion. J Pedodont 1981;5:281–94.

8. Wright CF. Crossbites and their manage-ment. Angle Orthod 1953;23:35–45.

9. Alexander WRG. The alexander disci-pline. Glendora (CA): Ormco; 1986:371–94.

10. Scuzzo G, Takemoto K. Invisible ortho-dontics. Berlin: Quintessence; 2003:15–21.

11. Lagravere MO, Flores-Mir C. The treat-ment effects of invisalign orthodonticaligners: a systematic review. J Am DentAssoc 2005;136:1724–9.

12. Wong BH. Invisalign A to Z. Am JOrthod 2001;121:540–1.

13. Womack WR, Ahn JH, Ammari Z,Castillo A. A new approach to correction

A B Figure 12. Radiographic views after orthodontic treatment: A, Panoramicview. B, Lateral cephalometric view.

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of crowding. Am J Orthod2002;122:310–6.

14. Boyd RL, Miller RJ, Vlaskalic V. TheInvisalign system in Adult Orthodontics:Mild crowding and space closure cases.J Clin Orthod 2000;34:203–12.

15. Kessler M. Interrelationship betweenorthodontics and periodontics. Am JOrtho 1976;70:154–77.

16. Buckley LA. The relationship betweenmalocclusion and periodontal disease.J Periodontol 1972;43:415–7.

Reprint requests: Jae Hyun Park, DMD,MSD, MS, PhD, Postgraduate OrthodonticProgram, Arizona School of Dentistry &Oral Health, 5855 East Still Circle, Mesa,AZ, USA 85206; Tel: 480-286-0455;fax: 480-668-3081; email: [email protected],[email protected]

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