American Journal of Orthodontics and Dentofacial Orthopedics
Case reportCanine-lateral incisor transposition: Controlling root resorption with a bone-anchored T-loop retraction
Section snippets
Diagnosis and etiology
The clinical examination of this 12-year-old girl in the permanent dentition showed an Angle Class II molar malocclusion with a complete transposition of the maxillary left canine and lateral incisor (Fig 1, Fig 2). The ectopic eruption of the maxillary left canine positioned it high in the vestibular fold between the central and lateral incisors (Fig 3, Fig 4).
From the patient's perspective, the anomaly was camouflaged by normal midlines and a functional deciduous canine, so the chief
Treatment objectives
The treatment objectives were to (1) establish functional Class I molar and canine relationships, (2) correct the transposition and restore natural tooth order, (3) create ideal overbite and overjet, (4) correct incisor inclinations and root angulations, and (5) improve facial esthetics.
Treatment alternatives
Compared with the mandibular arch, there are more therapeutic options for the maxillary dentition because the supporting bone is less dense. Esthetically and functionally, it is generally preferable to move transposed teeth to their normal positions in the arch.1
Consistent with the treatment objectives, the most conservative treatment plan was nonextraction alignment of the malposed teeth. Bilateral infrazygomatic crest (IZC) bone-screw anchorage was indicated to retract the transposed canine
Treatment progress
Treatment was started in the maxillary arch, with a 0.022-in passive self-ligation system (Damon 3mx; Ormco, Glendora, Calif); low-torque brackets were placed on the incisors. An open-coil spring was placed between the left central incisor and the first premolar to create space. One week later, the deciduous canine was extracted, and 2 OrthoBoneScrews (2 × 12 mm) with 0.022 × 0.028-in rectangular openings (Newton's A, Hsinchu, Taiwan) were inserted bilaterally in the IZCs, buccal to the
Treatment results
The transposed canine was successfully retracted to the ideal position in 5 months. The keratinized gingival tissue on the canine was normal; there was no gingival recession or dehiscence. The nasolabial angle was maintained, and a pleasant facial profile was achieved after 24 months of orthodontic treatment. The canine and molar relationships were corrected to Class I, and the upper, lower, and facial midlines were coincident (Fig 17). A functional occlusion was established with stable
Discussion
A successful orthodontic result is often predicated on the design of the force system.18 The IZC is a convenient placement site in the maxilla for orthodontic miniscrews or miniplates.19 It has been used successfully to provide skeletal anchorage for retraction of canines and incisors, both individually and en masse, as well as intrusion of the maxillary posterior teeth.20, 21, 22, 23, 24, 25 For our patient, an OrthoBoneScrews in each IZC was used to retract the entire maxillary arch to
Conclusions
A complete maxillary canine transposition is a complex anomaly that presents a significant orthodontic challenge. Conservative correction of the problem entails risks that require carefully controlled appliances. Segmented mechanics are optimal for individualized movement of target teeth. On the contrary, the use of continuous archwires for correction of a transposition invites adverse effects, particularly root resorption. For our patient, skeletal anchorage provided an independent force
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Cited by (17)
The relationship between local alveolar bone housing and size of canine in maxillary canine-lateral incisor transposition: A retrospective cone-beam computed tomography–based study
2022, American Journal of Orthodontics and Dentofacial OrthopedicsCitation Excerpt :This is in agreement with Lorente et al,25 who discussed that the higher the canine position in a patient with transposition, the greater the thickness of the local alveolar bone, and the more favorable it is to move with lower consequent risks. In practice, many researchers have taken segmented arch to maintain or appropriately depress the height of the canine to ensure that the canine moves at a relatively safe height.6,26 The incorrect positioning is subsequently corrected, and the tooth is retracted toward its normal position.
Temporary skeletal anchorage devices to correct challenging malocclusions with clear aligners
2021, AJO-DO Clinical CompanionContinuous archwire technique for the correction of completely transposed maxillary incisors
2021, American Journal of Orthodontics and Dentofacial OrthopedicsCitation Excerpt :His young age was the greatest advantage. When individualized and controlled movements of teeth are required, fixed appliances such as customized fabricated loops9-12 or cantilever15,19 are widely applied. In the current case, with the combination of 0.012-in NiTi archwire and 0.019 × 0.025-in SS archwire, a continuous archwire technique was employed to bypass the lateral incisor palatally.
The applications of TADs in canine transpositions
2018, Seminars in OrthodonticsCitation Excerpt :Although alignment of teeth in their transposed positions is more predictable, some patients may not be satisfied with accepting transpositions, due to the compromises in esthetics and/or function. There are some case reports in the literature describing orthodontic correction of transpositions.9,15–24 Most of these cases end up with long treatment times, less than ideal root parallelism, and gingival recession.9
Necessities of documentation in canine-lateral transposition
2017, American Journal of Orthodontics and Dentofacial OrthopedicsClass II division 1 malocclusion treatment trends in the last 10 years by skeletal classification: A review article
2023, Journal of International Oral Health
All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported.