2020, Number 2
Bilateral transposition of lower canines: clinical case report
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ABSTRACT
Introduction: Dental transposition is a term used to name extreme cases where there is an ectopic eruption, which causes a change in the natural placement of the permanent dentition. Clinical case: A 12-year-old female patient refers "my teeth came out the back"; she presents class I skeletal with a tendency to class III due to maxillary hypoplasia, class III right molar, class canine unestablished, straight profile and mixed dentition. Treatment with Alexander 0.018" fixed appliances, bite turbos in upper central incisors. Alignment and levelling phase: extractions of temporary canines, placement of buttons on lower canines to begin with the traction of canines towards the arch and couple mechanics. Working phase: incorporation of the cantilever for molar uprighting of the lower right second molar. Detailing and finishing phase: use of 3/16" 3.5 oz elastics in triangle shape, finalizing with removal of appliance and placement of retainer. Results: After two years and four months the objectives were achieved, in addition to the parallelization of the right lower second molar. Conclusion: Dental transposition has different aetiologies, therefore its correct diagnosis is important for successful treatment.INTRODUCTION
The canines are the longest, strongest and most important teeth in occlusion. They form a crucial part of the aesthetics of the face, providing harmony in the anterior region, complementing the smile line and the nasolabial fold, as well as having a valuable function when they are in the correct position. The permanent lower canines erupt at approximately 10.6 years of age and root completion occurs at 12.9 years of age.1-3
Canines have a high impaction rate and therefore require special attention. They are commonly impacted in the maxilla, while they are less likely to appear in the mandibular arch and less frequently to present a mandibular canine migrating to another site in the mandible. This phenomenon has been termed transmigration or movement of an unerupted tooth that has crossed the midline without the influence of any pathological entity, whereby the tooth may remain impacted or may also erupt in its new position.3,4
Dental transposition is a term used to name extreme cases where there is an ectopic eruption, which causes a natural change in the usual placement of the permanent teeth. In cases of dental transposition in mandibular canines, they rarely erupt and generate a transposition, as in most cases the canines remain as impacted teeth.5
The aetiology of dental transmigration or dental impaction is very varied and has not yet been determined, however, it is attributed to local or general factors or genetic pattern. Likewise, it may be the product of an alteration in dental development, resulting in malposition of the primary epithelial band during the embryological stage.3,6
In order to evaluate either a dental transposition or impaction, it is important to classify it. For this reason, the following points should be taken into account: first, determine whether the alteration is in the maxilla or in the mandible; second, observe whether it is unilateral or bilateral, on the left and/or right side; third, examine the depth with reference to the occlusal plane; fourth, analyse the radicular status; fifth, analyse the angulation, the central, vestibular, lingual and/or palatal presentation, and observe whether it has caused damage to neighbouring teeth.2
The treatment of dental transmigration can be complex and, depending on this, it could be a prolonged treatment, which is why extraction is suggested in cases with a poor prognosis.7
To achieve success in the alignment of the canines into the dental arch, some factors have been suggested that lead to a correct treatment, such as the cooperation of the patient; the age because it may require more treatment time; the space or crowding in the arch (as space will be needed to allow the new location of the canine in the arch) and finally the position of the canine. Therefore, it is of great importance to make a good diagnosis.6
Diagnosis should be based on two types of assessment: clinical and radiographic. Within the clinical evaluation, good clinical record keeping is an integral component in good professional practice, visual inspection and palpation should be carried out. There are several options for radiographic evaluation, including two-dimensional radiographies such as periapical, occlusal and panoramic, but they have disadvantages due to their distortion and superimposition on the structures. Another mechanism is computed tomography (CT) which provides the structures in three dimensions, its disadvantage is that the radiation is more intense than in a 2D. There is also cone-beam computed tomography (CBCT) which is of lesser radiation and provides the structures in sagittal, axial and coronal plane superimpositions.6
The following is the treatment of a patient with a class I skeletal malocclusion with bilateral lingual eruption of mandibular canines, treated with orthodontics and using Alexander appliances.
CLINICAL CASE REPORT
DiagnosisA 12-year-old female patient, with no medical history, whose reason for consultation was "My teeth came out the back".
The patient had a straight profile, brachyfacial facial pattern, diminished lower facial third, thin lip, facial asymmetry in the eye, eyebrow; nasal wing and mandible lower on the left side and nose deviated to the right (Figure 1A).
In the intraoral analysis the patient presents mixed dentition, right Class III molar, Class canine not established, ovoid-shaped upper and lower arch, short lingual frenulum, medium and square teeth, lower canines lingually out of the arch, deciduous canines present in the four quadrants (Figure 1B).
When analyzing the study models we can appreciate the inferior midline deviation 2 mm to the right, overjet 0.5 mm, overbite 3 mm and curve of Spee 3.5 mm. The Bolton analysis shows mandibular excess of 2 mm, in the anterior a mandibular excess of 2.4 mm, arch length discrepancy of 5 mm in superior and 6 mm in inferior, with slight anterior superior and inferior crowding (Figure 2).
Panoramic radiography showed patent paranasal sinuses, left turbinate with hypertrophy, symmetrical mandibular branches, symmetrical condyles, healthy bony crest levels, presence of the four primary canines, upper canines and the four unerupted second permanent molar teeth, third molar tooth germs in all four quadrants, and crown-root ratio of 1:1 (Figure 3A). The lateral cranial radiography (Figure 3B) shows a patent airway and a straight profile.
By means of the Steiner analysis, performed with Dolphin software version 9.0 (Table 1 and Figure 3B), the patient was diagnosed as a class I skeletal with a tendency towards class III due to a retruded maxilla, horizontal growth, brachyfacial facial pattern, upper incisor retroclination, retroclination and slightly retrusion of the lower incisors.
Treatment objectivesMaintain left class I molar and obtain right class I molar, traction canines to the mandibular arch and establish canine guidance, maintain oval arch form, eliminate curve of Spee, achieve overjet and overbite, and maintain profile.
Treatment alternatives- 1. The functions of microimplants include horizontal traction in canines and anchorage for molar uprighting. Their advantages are immediate loading, no osseointegration is required, there is no need for the growth to be complete, the surgical act of placement and removal is simple, but their disadvantage is the cost.
- 2. Monkey hooks is an auxiliary that consists of an open loop at each end. It is used as a tool in impacted canines, it directs the tooth into the correct position, its advantage is that several hooks can be placed in the form of elastic chains offering precise control and its disadvantage is the cost.
Treatment and progression
Treatment started without extractions and with Alexander 0.018" fixed appliances, placement of bite turbo in upper central incisors to lift the anterior bite, upper and lower arch 0.016" nitinol. Referred for interconsultation to extract primary canines. The lower arch was changed to 0.016" steel, button cementation on lower canines to start the dental alignment and levelling phase, together with traction of canines to integrate them into the arch (Figure 4). Placement of 0.012" lower nitinol archwire, cementation of bracket on left lower canine and button by lingual of right lower canine, to straighten the canine with couple mechanics.
The working phase started with 0.016" × 0.022" upper steel archwires and lower nitinol archwires, then a 0.017" × 0.025" upper steel archwire, and the placement of an open spring between lateral incisor and upper left first premolar maintaining the space of the canine. Placement of right lower tube in second molar, incorporating a titanium molybdenum (TMA) cantilever for positional correction (Figure 5). Removal of open spring and cantilever, and placement of bracket on upper left canine.
In the detailing and finishing phase, a 0.016" × 0.022" superior nitinol archwire was placed, a panoramic radiography was taken for root parallelisation. The use of 3/16" × 3.5 oz triangle elastics was indicated, the appliance was removed (Figure 6A), a 35 caliber essix retainer was indicated and an interconsultation with maxillofacial for third molar removal was performed.
RESULTS
A slight projection of the upper and lower lip was obtained in profile, which was associated with the retained growth. Intraorally the correct position of the canines within the arch was achieved, establishing a canine guidance and class I molar, adequate overjet and overbite, ovoid-shaped arches were maintained (Figure 6B), the Curve of Spee was eliminated, and the upright of the right second molar was obtained (Figure 7A). According to the Steiner analysis, the biggest change was in the lower incisors as they were retruded (Figure 7B), and an IMPA of 95.7o was obtained (Table 1). In the superimposition, the skeletal, dental and facial changes of the patient can be analysed (Figure 7C). With the changes made, the patient showed more confidence and satisfaction in smiling.
DISCUSSION
The case report describes the treatment of a class I skeletal patient with a lingually dental transposition of the lower canines and a mesioangulation of the left lower molar. Dental transmigration of mandibular canines is an uncommon anomaly,7 which is why it continues to be studied to date.
In a study by Al-Abdallah M et al,8 they analysed the presence of dental anomalies in 3,315 patients, where only one case of unilateral mandibular dental transposition was reported. Qadeer M et al.9 conducted a demographic study to understand the prevalence and patterns of impacted mandibular canines in 3,469 patients. They found 20 patients with this pathology, of which only 15% were bilateral, all of them being male and only 0.09% being dental transmigration. The particularity of the presence of this anomaly is clear, and the great significance and clinical interest of the current study, because it shows a female patient with bilateral dental transmigration of canines in the lower arch.
We agree with Sinko K et al.10 that, in order to determine the type of treatment to be performed in each patient, the characteristics of dental transposition should be taken into account, such as: associated pathology, age of the patient, complications and root position. In this way, a treatment option is pondered and an attempt is made to avoid the permanent tooth being surgically removed. Furthermore, it is agreed that the deciduous lower canine should remain in position and be removed before final alignment. Subsequently, the bracket is placed on the permanent canine in order to achieve correct levelling.
There are different techniques for the treatment of dental transmigration, as reported by Jaisinghani AP et al.11 In agreement with them, although the mechanics used in their case were not similar to those used by Sinko K et al, it can be speculated that the implementation of correct biomechanics can bring the transmigrated canines into occlusion.
Diaz-Sanchez RM et al. commented on the option of extracting teeth that are in transposition as a treatment,12 however, we disagree with them, because in some cases leveling and traction can be achieved with a good diagnosis and treatment plan.
In the study by Sinko K et al.10 they also mention the case of a lingual lower canine, where traction mechanics with microimplants was used with a treatment time of two years and 2.5 months. In comparison with the clinical case presented, the treatment time was two years and four months; highlighting that there is no significant difference, even though skeletal anchorage was not used.
Kim KJ et al.13 report that the use of microimplants in horizontally positioned molars allows control and brings the molar into its correct position. Since the positioning of horizontally impacted molars becomes a challenge in the praxis due to the limitation and control that can be achieved, in our case the use of microimplants was not chosen, due to the fact that the molar was slightly mesioangulated.
To solve this challenge, Loks A et al.14 mention that verticalisation of the teeth is necessary to restore occlusion, which is why they present different mechanics to perform it in molars, taking into account that side effects that could affect the final result should be avoided. For this reason, we decided to use a TMA cantilever, which allows longer activations with less force; the anterior teeth were used as anchorage, thus avoiding undesired extrusion and obtaining molar uprighting at the level of the occlusal plane, together with equilibrium in the occlusion.
CONCLUSION
Dental transposition in lower canines is a rare anomaly, but when it does occur, in most cases the canines are impacted and less frequently are in an ectopic eruption. What is relevant in this case is the ectopic eruption of both canines on the lingual side, so the decision was made to use Alexander appliances for bilateral dental traction, with which torque control was achieved. The use of TMA wire for the cantilever was advantageous in the molar uprighting, due to its great properties, obtaining parallelisation. With all these factors in favour, we concluded the case with a good occlusal relationship.
REFERENCES
Díaz-Sánchez RM, Castillo-De-Oyagüe R, Serrera-Figallo MÁ, Hita-Iglesias P, Gutiérrez-Pérez JL, Torres-Lagares D. Transmigration of mandibular cuspids: Review of published reports and description of nine new cases. Br J Oral Maxillofac Surg. 2016; 54 (3): 241-247. Available in: http://dx.doi.org/10.1016/j.bjoms.2016.01.010
AFFILIATIONS
1 Alumna de la Especialidad en Ortodoncia. Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. Guadalajara, Jalisco, México.
2 Egresada de la Especialidad en Ortodoncia. Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. Guadalajara, Jalisco, México.
3 Profesor de la Especialidad en Ortodoncia. Departamento de Clínicas Odontológicas Integrales. Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. Guadalajara, Jalisco, México.
CORRESPONDENCE
Erik Hernández Roldán. E-mail: erik.hz@hotmail.comReceived: Marzo 2021. Accepted: Junio 2021.