Fig. 1 Coronal cross-section of maxilla shows greater buccolingual alveolar width apically than coronally.
KAMBIZ MOIN, DMD, MPHSOGOLE MOIN, DMD, MDS
Orthodontic Management of Unerupted Transposed Canines
Drs. Kambiz Moin and Sogole Moin are in the private practice of orthodontics at 765 S. Main St., Suite 302, Manchester, NH 03102. E-mail Dr. Kambiz Moin at [email protected].
Dr. S. MoinDr. K. Moin
• Alignment of the teeth in their transposed posi-tions, followed by restorative camouflage treat-ment.• Extraction of one or both transposed teeth, fol-lowed by orthodontic treatment (especially recom-mended in severely crowded cases).• Orthodontic correction of the transposition.
Orthodontic treatment of canine transposi-tion is controversial. Some authors call it impos-sible,16 while others advise treating only a pseudo-transposition, where the root apex is in the normal location, in contrast to a true transposition.1
Because orthodontic treatment of canine transposition should always begin before eruption of the canine, an early diagnosis is key to a good result. An unerupted maxillary canine lies in an area of greater buccolingual alveolar bone width; due to the shape of the alveolar bone, however, the available width diminishes as the tooth erupts (Fig. 1). To move a canine past another tooth without damaging the roots and surrounding bone struc-ture, it is important to bond an attachment to the canine before it erupts into the oral cavity and, while holding it at that level, move it mesially or distally into proper position before bringing it
Transposition is a dental anomaly characterized by the positional interchange of two adjacent
teeth, especially in relation to their roots, or by the development and eruption of a tooth in a position normally occupied by a nonadjacent tooth.1 It is a rare phenomenon, with a prevalence of only .33%.2
Maxillary canine transpositions were first reported in the literature by Dr. E.M. Miel, a French dentist, who described three cases in 1817.3 Since then, various other authors have published cases of maxillary canine transpositions,4-12 and several studies have described their prevalence and characteristics.1,2,13,14
Maxillary Transpositions
Ciarlantini and Melsen described four op-tions for the treatment of transposed maxillary canines15:• Interceptive treatment, with the canine guided to erupt into its proper position after selective ex-traction of deciduous teeth.
Orthodontic Management of Unerupted Transposed Canines
first premolar (Fig. 2). The maxillary arch was bonded first, since there was more work to be done there than in the mandibular arch. After initial alignment, lingual root torque was applied to the upper left first premolar. The upper left canine was then surgically exposed and moved mesially, at the same occlusogingival level, by tying it with elastic thread to a vertical hook soldered to the archwire (Fig. 3A). The canine was later bracketed, and a
down into occlusion. Lingual root torquing of the maxillary first premolar or lateral incisor will move those roots out of the path of the erupting canine.
Case 1
An 11-year-old female presented with an up-per left canine erupting in transposition with the
Fig. 2 Case 1. 11-year-old female patient with upper left canine erupting in transposition with first pre-molar before treatment.
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Fig. 4 Case 1. Patient after 48 months of treatment.
Fig. 3 Case 1. A. Upper left canine surgically exposed and tied with elastic thread to hook on archwire for mesial traction. B. Round overlay wire placed to apply mesial root tip to canine.
A B
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Fig. 5 Case 2. A. 13-year-old female patient with transposed upper left canine and lateral incisor before treatment. B. Cone-beam computed tomography (CBCT) shows upper left canine lying coronal to lateral incisor.
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eted, and a round wire was bent passively to the level of the canine to continue distalization in the same occlusogingival plane while providing rota-tional and root control. A progress panoramic x-ray revealed that the lateral-incisor root needed uprighting (Fig. 6B); this was accomplished with a 2nd-order bend and a homemade uprighting spring (Fig. 6C). Treatment was completed in 33 months (Fig. 7).
Mandibular Transpositions
Mandibular teeth account for 25% of all transpositions.2 Two classifications are typically used17:• Transposition of the canine with the adjacent lateral incisor.• Transmigration of the canine across the sym-physeal midline to the other side of the arch.
Case 3
An 11-year-old male presented with bilateral transposition of the lower canines (Fig. 8A). CBCT imaging confirmed the transposed relationship of the left canine and lateral incisor (Fig. 8B); the right canine was in a similar position. Again, the affected arch was bonded first, since there was more work to be done there. The lower molars were banded; the remaining permanent teeth, ex-cept for the lateral incisors, were bonded. After initial alignment, an .016" × .022" archwire was
round wire with mesial root movement was overlaid on the main rectangular archwire for more root and rotational control (Fig. 3B). Once the canine was in the proper mesiodistal position, the first-premolar root torque was removed and the canine was brought into occlusion. After 35 months of treat-ment, a gingival graft was placed over the upper left canine to reinforce the attached gingiva; the case was debonded after a total of 48 months (Fig. 4).
Case 2
A 13-year-old female presented with a trans-position of the upper left canine and lateral incisor (Fig. 5A). Cone-beam computed tomography (CBCT) showed that the canine was lying coronal to the lateral incisor, with a slight space between them (Fig. 5B). After placement of fixed appli-ances, the left lateral incisor was moved lingually with a 1st-order bend and lingual root torque while its mesial inclination was maintained. The upper left canine was surgically exposed and tied with power thread to an .016" × .022" cantilever wire that was inserted in the headgear tube using a converter tube.* In its passive form, the canti-lever was bent buccally and upward to the level of the canine; when activated, it moved the canine labially, away from the root of the lateral incisor, as the tooth was distalized without extrusion (Fig. 6A). Twelve weeks later, the canine was brack-
Fig. 6 Case 2. A. Cantilever placed to distalize canine while pulling it labially. B. Twelve weeks later, prog-ress panoramic x-ray shows root angulation of upper left lateral incisor. C. Round wire placed to provide root and rotational control as canine distalization continues; 2nd-order bend and homemade uprighting spring employed to mesialize lateral-incisor root.
A CB
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inserted, and the patient was referred for surgical exposure of the lower canines. Cantilevers made of .016" × .022" wires with step-downs were then inserted into the double auxiliary tubes** on the main archwire. The cantilevers were bent to pull the canines labially, away from the lateral incisors, while preventing their eruption (Fig. 9A). Once the lateral incisors were bonded, 1st-order bends were used to move them lingually away from the ca-nines. The cantilever wires were shortened, so that the canines were pulled distally as well as labially (Fig. 9B). Finally, the canines were bracketed;
uprighting springs made of .016" Australian wire*** were used to move their roots distally, while their crown positions were maintained by tying them to the posterior teeth (Fig. 9C). After 44 months of orthodontic treatment, gingival grafts were placed at the canines to enhance the attached gingival tissue (Fig. 10).
**TP Orthodontics, Inc., LaPorte, IN; www.tportho.com.***Registered trademark of A.J. Wilcock Pty. Ltd., Whittlesea, Victoria, Australia. Distributed in North America by G&H Wire Company, Franklin, IN; www.ghwire.com.
Fig. 7 Case 2. Patient after 33 months of treatment.
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the midline to below the apex of the right lateral incisor (Fig. 11B). After initial alignment, the pa-tient was referred for surgical exposure of the low-er left canine. The surgeon was instructed to fully expose the crown of the canine and to place the
Case 4
An 11-year-old female presented with an un-erupted lower left canine (Fig. 11A). CBCT imag-ing showed that the tooth had transmigrated across
Fig. 8 Case 3. A. 11-year-old male patient with bilateral transposition of lower canines with lateral inci-sors before treatment. B. CBCT shows positions of lower left ca-nine and lateral incisor.
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B
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Fig. 10 Case 3. Patient after 44 months of treatment.
Fig. 9 Case 3. A. Bilateral cantilevers used to pull canines labially, away from lateral incisors, while main-taining their inferior position. B. Shortened cantilever pulls canine distally and labially. C. Uprighting spring placed to move canine root distally; canine bracket tied to first-premolar bracket to prevent canine crown from moving mesially.
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Fig. 11 Case 4. A. 11-year-old female patient with unerupted lower left canine before treatment. B. CBCT shows left canine below apex of right lateral incisor.
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surgical attachment with chain as far distally and as close to the cementoenamel junction as possible for optimum rotational and root control. An .016" × .022" cantilever wire with a step-down was in-serted into a double auxiliary tube slid onto the lower wire. When activated with power thread, the cantilever moved the canine labially, away from the incisors, and distally without extrusion (Fig. 12).
As the canine was distalized, the cantilever wire was shortened. Since the chain was emerging from mucosal tissue, soft-tissue overgrowth occasion-ally needed to be removed with a laser to re-expose the chain (Fig. 13). Once the canine had passed the left lateral incisor (Fig. 14), the sectional wire was adjusted to extrude the tooth. After eruption, the canine was bracketed and brought into its proper position. No gingival graft was necessary. Treat-ment was completed in 31 months (Fig. 15).
Discussion
Although correction of a transposition is fair-ly complex, it can be a great service to the patient and a rewarding experience for the orthodontist. All factors, including the position of the root apices, esthetics, occlusion, patient cooperation, and length of treatment, should be considered in determining the treatment plan. A close working relationship with the oral surgeon is a must, and three-dimen-sional imaging is helpful. Careful planning and continuous reevaluation of mechanics are required to avoid damage to the teeth and supporting struc-tures. There is no magic bracket or prescription.
Orthodontic correction is not advisable in every case. On the patient’s side, it requires time, full cooperation, and an appreciation of the treat-ment objectives. From the orthodontist, it requires patience, creativity, and dedication to achieving the best result—even if it is not financially profitable.
Fig. 12 Case 4. A. Cantilever wire activated by tying it to surgical chain on transposed canine. B. Canti-lever in passive position (dashed lines).
Fig. 13 Case 4. Surgical chain re-exposed using soft-tissue laser to eliminate overgrowth.
Fig. 14 Case 4. Lower left canine distalized and uprighted after 22 months of traction.
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Fig. 15 Case 4. Patient after 31 months of treatment.
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REFERENCES
1. Peck, S. and Peck, L.: Classification of maxillary tooth trans-positions, Am. J. Orthod. 107:505-517, 1995.
2. Papadopoulos, M.A.; Chatzoudi, M.; and Kaklamanos, E.G.: Prevalence of tooth transposition, a meta-analysis, Angle Orthod. 80:275-285, 2010.
3. Miel, E.M.: Observation sur un cas très-rare de transposition de dents, J. Méd. Chirurg. Pharm. 40:88-97, 1817.
4. Shapira, Y.; Kuftinec, M.M.; and Storm, D.: Maxillary ca-nine-lateral incisor transposition: Orthodontic management, Am. J. Orthod. 95:439-444, 1989.
5. Maia, F.A.: Orthodontic correction of a transposed maxillary canine and lateral incisor, Angle Orthod. 70:339-348, 2000.
6. Kuroda, S. and Kuroda, Y.: Nonextraction treatment of upper canine-premolar transposition in an adult patient, Angle Orthod. 75:472-477, 2005.
7. Vitale, C.; Militi, A.; Portelli, M.; Giancarlo, G.; and Matarese, G.: Maxillary canine-first premolar transposition in the permanent dentition, J. Clin. Orthod. 43:517-523, 2009.
8. Giacomet, F. and Araújo, M.T.: Orthodontic correction of a maxillary canine-first premolar transposition, Am. J. Orthod. 136:115-123, 2009.
9. Capelozza Filho, L.; Cardoso, M.A.; An, T.L.; and Bertoz, F.A.: Maxillary canine-first premolar transposition, Angle
