CASE REPORT

Orthodontic correction of a transposed maxillarycanine and first premolar in the permanentdentition

Kazuaki Nishimura,a Kimihisa Nakao,b Taijyu Aoki,a Mariko Fuyamada,c Keisuke Saito,c and Shigemi Gotod

Nagoya, Japan

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524

The patient was a 16-year-old Japanese girl whose chief complaints were crowding and transposition of themax-illary canine and first premolar. A setup model was used to preoperatively align the teeth in their transposed po-sitions. The amount of postoperative reshaping was estimated for the occlusal surfaces of the teeth. However,the patient did not wish to have her teeth reduced by reshaping or to have composite materials for restorativecamouflage. Because she strongly expected alignment of her teeth in the correct intra-arch position, her trans-posed teeth were corrected without extraction of the transposed teeth. Cone-beam computed tomography wasused to obtain more detailed information about the transposition, and the direction of tooth movement was ex-amined. Although the duration of the treatment was long, both the crowns and the roots of the transposed teethwere aligned correctly. (Am J Orthod Dentofacial Orthop 2012;142:524-33)

Transposition of teeth is defined as an interchangeof position of 2 teeth in the dental arch, and its in-cidence is relatively rare.1,2 The maxillary canine

and first premolar transposition is most frequentlydescribed in the literature, followed by transpositionof the maxillary lateral incisor with the canine.Unilateral transpositions have been reported moreoften than bilateral transpositions, and the left sidehas been more frequently involved than the right.3-5

Transposition can be complete or incomplete.3 In a com-plete transposition, both the crowns and the entire rootstructures of the involved teeth are found in their trans-posed positions. In an incomplete transposition, thecrowns might be transposed, but the root apices still re-main in their normal positions. Several factors should beconsidered when making an orthodontic treatment planfor transposed teeth. In extraction treatment, many pa-tients are treated by extraction of either tooth. In

the Department of Orthodontics, School of Dentistry, Aichi-Gakuin Univer-agoya, Japan.tant professor.uctor.raduate student.ssor and chairman.uthors report no commercial, proprietary, or financial interest in the prod-r companies described in this article.t requests to: Kazuaki Nishimura, Department of Orthodontics, Aichi-n University, School of Dentistry, 2-11 Suemoridori, Chikusaku, Nagoya651, Japan; e-mail, kazuaki@dpc.aichi-gakuin.ac.jp.itted, December 2010; revised and accepted, January 2011.5406/$36.00ight � 2012 by the American Association of Orthodontists./dx.doi.org/10.1016/j.ajodo.2011.01.027

nonextraction treatment, patients undergo alignmentof teeth in their normal positions or in their transposedpositions. Whichever treatment is selected, several fac-tors (positions of the crowns and roots, gingivae of thetransposed teeth, caries risk, and duration of treatment)should be considered when making an orthodontictreatment plan for transposed teeth. This case reportdemonstrates the successful alignment of a completemaxillary canine and first premolar transposition in theirnormal positions with nonextraction treatment. Goodresults have been maintained for 2 years after active or-thodontic treatment.

DIAGNOSIS AND ETIOLOGY

The patient was a 16-year-old Japanese girl. Herchief complaints were crowding and transposition ofthe maxillary right canine and first premolar. She hadno orthodontic history. The pretreatment facial photo-graphs showed a symmetric facial pattern with a straightprofile (Fig 1). The intraoral examination showed an An-gle Class III molar relationship bilaterally. All permanentteeth were erupted, and the maxillary right deciduouscanine was retained. The maxillary right permanent ca-nine had erupted in an ectopic position between the 2premolars. The maxillary right first premolar was in scis-sorsbite. The arch length discrepancies were –4.3 mm inthe maxillary arch and –1.9 mm in the mandibular arch.She had 13.0 mm of overjet and 12.0 mm of overbite.Both maxillary and mandibular dental midlines nearlycoincided with the facial midline (Figs 1 and 2). On

Fig 1. Pretreatment facial and intraoral photographs.

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radiographic examination, the root of the maxillary rightdeciduous canine was mostly resorbed, and both thecrowns and the roots were transposed (Fig 3). Dentalcomputed tomography scans showed that the root ofthe right canine was between the premolars, and theroot of the first premolar was close to the crown of thecanine but not resorbed (Fig 4). Maxillary canine andfirst premolar transposition is the most frequent typeof transposition. Several etiologies of transpositionhave been proposed: genetic origin, trauma, interchangeof the position of the developing tooth buds, lack ofdeciduous canine root resorption, early loss of deciduousteeth, and prolonged retention of deciduous teeth.Because of the high incidence of retained deciduouscanines associated with tooth transpositions, some au-thors have reported that deciduous teeth are the primaryetiologic factor of this anomaly. In this patient, a possibleetiology of transposition included the retained decidu-ous canine. In the lateral cephalometric radiograph,

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the maxilla was positioned posteriorly, and the mandiblewas positioned normally relative to Japanese standards(SNA, 78.2�; SNB, 76.7�; ANB, 1.5�). The patient hada skeletal Class III relationship. The inclination of themaxillary incisors was normal, but the mandibular inci-sors showed a lingual inclination (Fig 5, Table). Fromthese findings, the patient was diagnosed with an AngleClass III malocclusion with crowding and transpositionof the maxillary right canine and first premolar.

TREATMENT OBJECTIVES

The treatment objectives were to correct the transpo-sition, establish the natural tooth order by extraction ofthe maxillary right deciduous canine without extractionof the transposed tooth, establish a functional Class Imolar and canine relationship with coincident dentalmidlines, create ideal overbite and overjet, and correctthe lingual inclination of the incisor.

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Fig 3. Pretreatment panoramic radiograph.

Fig 2. Pretreatment dental casts.

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TREATMENT ALTERNATIVES

The following alternatives were considered for thetransposed teeth: (1) extraction of all first premolars,(2) extraction of the maxillary right canine or first pre-molar, (3) nonextraction treatment and alignment ofthe teeth in the transposed order, and (4) nonextractiontreatment and correction of the transposition.

In considering these treatment alternatives, the fol-lowing factors were taken into account. Because the fa-cial appearance was satisfactory for a Japanese girl, shedid not need retraction of the lips. Treatment with ex-traction of the 4 first premolars would have required ex-tensive linguoclination of the maxillary and mandibularincisors, or it would have required extensive mesialmovement of the molars.

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In addition, if either the maxillary right first premolaror the canine had been extracted, that dental arch wouldhave become asymmetric, and the treatment mechanicswould have become difficult. Therefore, we evaluatedhow the transposed teeth could be aligned without toothextractions. Because both the crown and the root weretransposed in the maxillary right first premolar and ca-nine, aligning the teeth in the transposed order wouldprobably have required a shorter treatment time thancorrecting the transposition. Correction of a transposi-tion poses a high risk of damaging the teeth or the sup-porting structures. Thus, alignment of the involved teethin their transposed positions seemed to be the best alter-native, but the patient strongly desired alignment of theteeth in their correct positions. Dental computed tomog-raphy showed that the roots of the transposed teeth werein close proximity, but root resorption was not observed.From a diagnostic setup model (Fig 6), if the teeth wereto have been aligned in their transposed positions, ex-tensive reshaping and camouflage restoration mighthave been required.6 We decided to attempt treatmentwithout extraction of the transposed tooth and with cor-rection of the transposition to achieve a functional ClassI canine and molar relationship.

TREATMENT PROGRESS

After the maxillary right deciduous canine was ex-tracted, a transpalatal arch and a lingual arch wereplaced on the maxillary arch as anchorage. The maxillary

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Fig 4. Pretreatment dental computed tomography scans.

Fig 5. Pretreatment cephalometric radiograph.

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right first premolar was protracted with an elastic chainin a palatal direction with an intentional mesial rotation(Fig 7). The mesiodistal root width of the maxillary firstpremolar was narrower than its buccolingual diameter.Therefore, we mesially rotated the first premolar to pre-vent its contact with the canine root. In addition, thecanine was mesially protracted with an elastic chainfrom a buccally extended hook off the lingual arch.The positional relationship between the canine and firstpremolar improved after 3 months of treatment. Thus,edgewise appliances (0.018 3 0.025 in) were placedon the maxillary teeth. Mesial movement of the maxillaryright canine began with the placement of an open-coil

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spring between the canine and the second premolar(Fig 7). The first premolar was aligned in the dentalarch, while improving its rotation (Fig 7). At 16 months,edgewise appliances were placed on the mandibularteeth. Attainment of correct intercuspation, and idealtorque and root parallelism were considered. Forty-eight months later, all edgewise appliances were re-moved, and bonded retainers and wraparound retainerswere fabricated to maintain the alignment.

TREATMENT RESULTS

Adequate facial proportions were obtained at the endof treatment (Fig 8), and the upper and lower lips wereslightly retruded. The facial photographs showed a pleas-ant smile. The crowns and roots of the transposed teethhad been corrected and were in their proper positions.The gingivae of the transposed teeth showed no signsof inflammation. The interproximal sulcus depth wasabout 2 mm (Figs 8 and 9). Radiographically, root paral-lelism was acceptable. Slight root resorption was ob-served on both transposed teeth (Fig 10). A computedtomography scan showed triangular bone resorption atthe vestibular cortical bone of the maxillary right canine(Fig 11). The cephalometric superimposition showeda clockwise pattern of mandibular rotation growth.The labially inclined maxillary incisors and lingually in-clined mandibular incisors at pretreatment were im-proved (Table, Figs 12 and 13). A good occlusion wasachieved. These results have been maintained for 2 yearsafter active treatment. A computed tomography scanshowed that part of the cortical bone was restructured,and a regular cortical contour was observed (Figs 14and 15).

DISCUSSION

In general, 2 treatment alternatives were consideredwith nonextraction of the transposed tooth3,4:alignment of the teeth in their transposed positions,

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Fig 6. Diagnostic setup model.

Table. Cephalometric measurements

Measurement Mean SD Pretreatment Posttreatment Two years posttreatmentSNA (�) 82.3 3.5 77.5 78.0 78.0SNB (�) 78.9 3.5 76.0 75.1 75.2ANB (�) 3.4 1.8 1.5 2.9 2.8FMA (�) 28.8 5.2 29.7 30.6 30.6Gonial angle (�) 122.2 4.6 125.8 123.3 123.3Ramus inclination (�) 2.9 4.4 6.1 2.7 2.7Occlusal plane to FH (�) 11.4 3.6 10.2 15.9 15.5U1 to SN (�) 104.5 5.6 111.1 97.3 98.0FMIA (�) 58.0 66.8 59.4 60.2

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and orthodontic tooth movement to the correct intra-arch position.

Many reports discuss improvements of transposedteeth orthodontically.7-12 In general, when thetransposed teeth are almost completely erupted, thetreatment involves alignment in the transposedpositions3,13,14 or extraction of 1 tooth or bothteeth, followed by orthodontic correction.15-17 Thedisadvantages of aligning the teeth in the transposedorder are esthetic and functional problems. If the rightcanine and first premolar had been aligned in theirtransposed positions, the diagnostic setup modelindicated that the right first premolar would haverequired reshaping of its occlusal surface andrestorative camouflaging of its small buccal cusp withcomposite materials.18 Thus, the esthetics might have

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been compromised. However, because the buccal cuspof the first premolar was small, restorative camouflagetreatment would have been required by using compositematerials. In addition, it was thought that the lingualcusp hindered lateral movement of the mandible, and re-duction of the lingual cusp would have been needed.There was a risk of pulpectomy, because it would havebeen necessary to either reshape the first premolar con-tour over a wide area or perform crown prosthesis treat-ment. The disadvantages of attempting to correcttransposed teeth are the potential risk of damage tothe roots or the supporting structures, or the potentiallyprolonged treatment. There were some disadvantages inboth treatment plans, but orthodontic management ofthe transposition was selected because of the desires ofthe patient and her family. The panoramic, periapical,

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Fig 7. Progress intraoral photographs.

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and occlusal radiographs would have been useful forconfirming the root position, but we decided to takea dental computed tomograph instead to better assessthe positions of the canine and the premolar. Dentalcomputed tomography is useful in a thorough examina-tion of the position of impacted and transposed teeth,and it allows dentists to obtain 3-dimensional informa-tion without exposing patients to high levels of radiationfrom medical computed tomography scans.19,20 Thedental computed tomograph showed neither rootcontact between the canine and the first premolar norroot resorption. It was thought that adequatedisplacement was possible if we paid attention to the

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direction of movement of the tooth roots. Themaxillary right first premolar was moved in a palataldirection with accompanying mesial rotation. Rootcontact was thought to have been prevented at thetime of canine mesial drifting, because the mesiodistalroot width of the premolar was narrower than itsbuccolingual diameter. Mesial drifting was initiallyperformed to prevent lingual tipping of the canineroot as much as possible, so that a standard edgewisebracket (0� torque) could be placed on the maxillaryright canine.

These procedures seemed to produce favorable con-ditions to minimize the risk of root contact during tooth

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Fig 8. Posttreatment facial and intraoral photographs.

Fig 9. Posttreatment dental casts.

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Fig 10. Posttreatment panoramic radiograph.

Fig 11. Posttreatment dental computed tomographyscan.

Fig 12. Posttreatment cephalometric radiograph.

Fig 13. Cephalometric superimpositions of pretreatmentand posttreatment tracings.

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movement. However, a long treatment time was neededto control the distal movement of the maxillary right firstpremolar root and the maxillary right canine torque. Thegingivae of the transposed teeth showed no signs of in-flammation. The interproximal sulcus depth was about 2mm. A computed tomography scan showed labial alveo-lar bone resorption after treatment. However, the scansshowed that part of the bone tissue regenerated 2 yearsafter treatment. It was thought to have led to a goodtreatment result in which a healthy periodontium wasmaintained, since the patient was young. The patientof Babacan et al10 was 15 years old at posttreatment,and our patient was 20 years old. Both patients were rel-atively young, and Babacan et al thought that the youngage might have positively affected tissue regeneration.

CONCLUSIONS

Dental transpositions can be corrected orthodonti-cally. However, the mechanics are complex, treatment

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Fig 14. Two-year posttreatment intraoral photographs.

Fig 15. Two-year posttreatment computed tomographyscan.

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time is long, and dental tissues can be damaged. The pa-tient's compliance, esthetics, function, caries risk, andage should all be considered when deciding whethertreatment of a transposition should involve tooth ex-tractions, tooth alignment in the transposed order, or or-thodontic correction of the transposition. A diagnosticsetup model and computed tomography were effectiveand important in determining the appropriate treatmentplan for our patient's transposed teeth.

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2. Rakosi T, Jonas I, Graber TM. Orthodontic diagnosis. New York:Thieme Medical Publishers; 1993.

3. Shapira Y, Kuftinec MM. Tooth transpositions—a review of the lit-erature and treatment considerations. Angle Orthod 1989;59:271-6.

4. Peck S, Peck L. Classification of maxillary tooth transpositions. AmJ Orthod Dentofacial Orthop 1995;107:505-17.

5. Peck L, Peck S. Maxillary canine-first premolar transposition, asso-ciated dental anomalies and genetic basis. Angle Orthod 1993;63:99-109.

6. Ciarlantini R, Melsen B. Maxillary tooth transposition: correct oraccept? Am J Orthod Dentofacial Orthop 2007;132:385-94.

7. Bocchieri A, Braga G. Correction of a bilateral maxillary canine-first premolar transposition in the late mixed dentition. Am J Or-thod Dentofacial Orthop 2002;121:120-8.

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13. Demir A, Basciftci FA, Gelgor IE, Karaman AI. Maxillary caninetransposition. J Clin Orthod 2002;36:35-7.

14. Parker WS. Transposed premolars, canines, and lateral incisors. AmJ Orthod Dentofacial Orthop 1990;97:431-48.

15. Rabie AB, Wong RW. Bilateral transposition of maxillary canines tothe incisor region. J Clin Orthod 1999;33:651-5.

16. Sato K, Yokozeki M, Takagi T, Morigama K. An orthodontic case oftransposition of the upper right canine and first premolar. AngleOrthod 2002;72:275-8.

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17. Maia FA. Orthodontic correction of a transposed maxillary canineand lateral incisor. Angle Orthod 2000;70:339-48.

18. Proffit WR, Fields HW Jr, Ackerman JL, Thomas PM, Tulloch JFC.Contemporary orthodontics. St Louis: Mosby; 1986. p. 188-9.

19. Ludlow JB, Ivanovic M. Comparative dosimetry of dental CBCTdevices and 64-slice CT for oral and maxillofacial radiology.

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Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:106-14.

20. Naitoh M, Hiraiwa Y, Aimiya H, Gotoh K, Ariji E. Accessory mentalforamen assessment using cone-beam computed tomography.Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;107:289-94.

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