Employment of Two-Plan Loop Correction for Dental TranspositionTreatment in Orthodontics: Report of Two CasesPicanço PRB, Picanço GV, Lima FC, Dantas TCFB, Marçal FFDepartment of Orthodontics, Paulo Picanço School of Dentistry, Fortaleza, Brazil

AbstractThe aim of this article was to show two cases that used a two-plan loop (T-loop modified) for correcting of dental transposition. Thecases showed orthodontic treatments of transposition between lateral incisor and canine treated by two-plan loop. The loop modifiedshowed as a good option to correct transposition with minor possibility of periodontal trauma due the horizontal movement withdecreased vertical vectors. Only in second phase vertical movements occurred in order to include the canines in the main arch. Thecorrection was satisfactory and it showed as a viable possibility in the orthodontic clinics offering to the patient a movement moresafety and controlled in the vertical dimension.

Key words: Orthodontics, Corrective orthodontics, Tooth transposition

IntroductionThe transposition is the alteration of the original place of theirruption of the dental element. This alteration can becompleted when the crown and root show in the differentcorrect place or incomplete when only the crown is out of itsoriginal position, keeping the root correctly in its originalplace [1]. The incidence of transposition is about 0.4% of allmalocclusions [2], similar incidence also found by othersauthors (0.51%) [3].

The incidence of teeth with transposition in maxillary isbigger, where the minor of the cases shows bilateral incidence[4]. In mandible, the transposition more common is betweenthe canine and the lateral incisor, being rare the transpositionbetween canine and premolar. The biggest incidence oftransposition is female gender [5,6]. In 1995, Peck et al. [7]classified the transposition in the following 5 types: canineand premolar (superior), canine and lateral incisor (superior),canine and first molar (superior), lateral and central incisive(inferior); lateral incisive lateral e canine (inferior). Theincidence of the transposition is most common in superiorarch, as related by Brezniak et al. [8]. Moreover, cases oftransposition with inferior canines are uncommon in scientificliterature. In 1999, Taner et al. [9] considered the extraction ofinferior canine transposed as a therapeutic option.

The transposition and its orthodontic correction show as achallenger approach. Although the literature indicates thismalocclusion as viable to be treated it is little discussed aboutdifferent ways to treat this alteration and its limitationsassociated to convectional mechanics. Thus the aim of thepresent article is to relate two cases of treatment of dentaltransposition of the canine with the lateral incisor using a two-plan loop.

Case Presentation

Case 01: Diagnosis and treatment

Brazilian patient, female gender, age 11 years old and 2months (Figure 1), were attended to Center of OrthodonticsPaulo Picanço (Fortaleza, Brazil) for orthodontic evaluationand treatment. The patient shows Angle Class I malocclusionin the final of the mixed dentition (Figure 2). Moreover, the

patient showed deviated midline, bad formation of the rightlateral incisor in transposition with the right inferior caninelocalized in horizontal position next to midline (Figures 2 and3).

Figure 1. Case 1, facial aspects pretreatment. Biprotrusion perfil.

Figure 2. Case 1, Intraoral aspects pretreatment. Anglemalocclusion Class I.

Corresponding author: Dr. Paulo R. B. Picanço, Department of Orthodontics, Paulo Picanço School of Dentistry, Fortaleza-CE,Brazil, Tel: 55 85 982053222; E-mail: paulopicanco@facpp.edu.br

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Figure 3. Case 1 - Panoramic radiography of the pretreatment.

Two options of treatment were considered: first theextraction of the teeth 42 and 43 and the maintenance ofspaces for future setting of implants. The other option is theextraction of the tooth 42 and traction of the dental element 43though its favorable situation. The patient was treated withpreset Edgewise (American Orthodontics). It was performedaccess by surgery procedure for the bonding of an attachmentin the right inferior canine and it was realized a first tractionwith steel ligature wire for verticalise the canine. After thisstep, it was held the confection of a continuous arch with anextensive T-loop modified for keep the movement of theinferior canine in a plan more inferior than others teeth(Figure 4). This loop has as propose to facilitate the pass ofthe dental element 43 below the teeth avoiding the cervicaldiameter of the tooth 42 in order to avoid dehiscence in regionof dental alveolus. It was used a steel wire 0.014’’ forconfection of the loop in order to avoid resistance in thecorrection of the canine passing through the teeth. Thisthickness of wire was chosen for allowing freedom ofmovement avoiding the radicular resorption.

Evolution of the treatment

During the treatment, it was performed the building of theappliance preset Edgewise slot 0.22×0.25 (AmericanOrthodontics), the right inferior canine was moved forcorrecting the transposition. The movement of the canine washeld in the direction of the midline in the original region ofthe canine. For this correction of the inferior canine, it wasdefined the use of a continuous wire with the T-loop forperforming the traction of the canine do canine supported inthe continuous arch for avoiding the mesialization of thecrown in direction to distal force and rotation of the canineduring its movement (Figures 4 and 5).

Figure 4. Case 1, mechanics of the two-plans loop.

Figure 5. Case 1, aspects of the continuou arch after correction ofthe canine in its original place.

Figure 6. Case 1, postreatment with good facial aesthetics.

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Figure 7. Case 1, after extraction of the 42 (case concluded with 3inferior incisors).

Figure 8. Case 1, final panoramic radiography.

Figure 9. Computational design of the two-plans loop.

After 2 years and 6 months of orthodontic treatment, it wasconcluded the treatment with corrected occlusal guides,without overjet though of the extraction of the bad formedinferior incisive (Figures 6 and 7) and good cephalometricvalues. The offer of a minimum recession of the right inferiorcanine was possible due the incorporation of lingual roottorque. The treatment shows a good result though a need ofextraction of the inferior lateral incisive. There was aconsidered improvement in the profile due a verticalization

and intrusion of the molars (Figures 8 and 9). Moreover, themandible rotated anticlockwise.

Figure 10. Case 2, facial aspects of the pretreatment.

Figure 11. Case 2, angle class I malocclsuion, retention of theright superior deciduous canine.

Figure 12. Case 2 – initial panoramic radiography.

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Figure 13. Case 2-use of the two-plans.

Figure 14. Case 2, two-plans loop for position the canine andfinalize the corrections of the transposition.

Figure 15. Case 2, two-plans loop for correcting of superiordental transposition.

Figure 16. Case 2, intra-oral aspects after the creation of thetransposition.

Figure 17. Case 2, extraoral aspects after the correction of thetransposition.

Case 02: Diagnosis and treatment

The second case is a Brazilian patient, male gender, 12 yearsand 4 months (Figure 10), Angle malocclusion Class I, inpermanent dentition, ported of a incomplete transpositionbetween the right superior lateral incisor and the caninesituated by vestibular side (Figures 11 and 12). The patienthas indication to perform orthodontic treatment withextraction of 4 due the biprotrusion dento-alveolar. Twooptions of treatment were chosen: the extraction of the teeth13, 24, 34 and 44, without correction of the transposition orextraction of the four first-premolars after success oftransposition between the teeth 13 and 12 (Figure 13). Thepatient was treated with the appliance preset Edgewise, Roth(Morelli). It was also performed surgery access for bondingattachment in the transposed tooth. The referred tooth wasexposed for being localized in keratinized gingiva.

Evolution of the case

During the orthodontic treatment, it was performed thebuilding of the appliance preset Edgewise, slot 0.22×0.25(Moreli) (Figures 14 and 15). The two-plan loop was realizedwith the steel wire 0.014’’ to start the movement and it was

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evolved until the steel wire 0.020’’ searching to offer freedomfor a movement of root of neighbor teeth.

During the correction of the right superior canine, the rightsuperior first premolar was preserved until the assurance ofthe success of the correction of the transposition (Figure 16).The canine was found in region of the inserted gingiva, thebonding of the bracket was held with the opened crown.Besides that it were observed adequate periodontal contourafter the correction of the canine.

The phase of the correction of the transposition by the two-plans was finalized and it showed satisfactory (Figures 16 and17). In case of transposed canine is more anterior to the archof two-plan and it was necessary to make a curve in order toadequate a loop to the anatomy of the case (Figure 15). Theextraction of 4 first molars only was performed after thesuccess of the transposition. It was used two Bull loopstargeting to close spaces in the arch. After these photos, thepatient did not return to the orthodontic attendance in the citedcenter due change of habitational city. By the other hand thetransposition was corrected.

DiscussionTeeth transposition is a complex and challenger malocclusionin Orthodontics, being considered complete when crown androot are found transposed or incomplete when the crown istransposed and the root is observed not transposed [10-12].The present manuscript related therapeutic orthodontictreatment for cases of incomplete transposition in which thecanine and lateral incisors were transposed. The occurrence ofunilateral transposition is higher than bilateral [13,14], asobserved in the cases depicted. Furthermore, thetranspositions were encountered one in superior arch and theother in the inferior arch. Nevertheless, most cases oftranspositions are located in upper arch, once literaturedemonstrated twenty times higher incidence of transpositionin upper than in lower arch.

The handling of dental transposition requires a complexbiomechanics, most often quoted in literature solved by thesegmented arch technique [13-16]. The orthodontic mechanicemployed in the present cases was a two-plan loop with amodified T-loop targeting first the treatment of horizontal plantransposition, preventing the teeth to move vertically in dentalregion. A second step (without loop) was undertakenextruding the teeth for the proper insertion in the arch. Oneconventional T-loop was already cited as a treatment optionfor adjustment of transposition [14]. The main difference ofthe loop proposed in the present investigation is the likelihoodto avoid distalization force coming from further dentalelement or external device. Indeed, the curvature of the two-plan loop might work as anchoring for the attachment whichwill distalize the tooth in first step. Other authors reported theadvantages of transposition correction in a continuous arch[17].

A recent investigation advocated the extraction oftransposed canines, when they are next to neighboring teeth orwhen too misplaced [18]. However, specifically in the Case 1,it was not a feasible alternative, once right lower lateralincisor was previously extracted due to crown and radicularmalformation which impaired the aesthetic prognosis of the

patient. In Case 2, the patient presented incompletetransposition between right upper canine and right upperlateral incisor. The canine of second report was initiallypositioned in inserted gingiva and, thus, was treated withouttorque control. According to Ileri et al. [10], the orthodontictreatments realized without tooth extraction resulted in afavourable final condition. The increase in inclination oflower incisors towards buccal direction was reported byKokich [11] in cases with extraction of lower incisor, whichwas not needed in the present Case 2.

The middle line deviation observed before the correction inCase 1 was explained by the position of right lower lateralincisor and canine in transposition nearby middle line. Theoption to undertake the extraction of element 42 could aid tocorrect the middle line deviation and avoid the need for animplant thereof. Most complex factor in Case 1 was tomaintain the position of canine during the correction oftransposition, as the tooth should not move upwards beforethe right time as well as should move straight without turningto side directions. This required an inclination of the loop toavoid such condition. The patient had the option to undergoright upper canine extraction rather than extraction of rightupper first premolar, but, in order to keep the function ofcanine, it was decided to correct transposition of canine andextract first premolar.

During transposition correction, the tooth was subjected toorthodontic traction through the oral mucosa favouringgingival recession, but the application of lingual torque of rootcontrolled the recession during finalization phase. A strikingrisk exists during orthodontic traction, as transposed caninelacks a guide for movement. In the case of two-plan loop,horizontal guide is characterized in first plan by the referringloop. This guide plays a fundamental role in avoidingincorrect movement of root towards neighbour teeth, which ispointed out as one of the main reasons for periodontal sequels[14]. The prognosis of inserted gingiva at the end oforthodontic traction possesses direct correlation with tractionmechanics according to Kokich [9].

The canines positioned in inserted gingiva or in palatemight be pulled in open way, without the risk for periodontalnegative effects at the end of the treatment. Canine localizedin keratinized gingiva when pulled in open way might bringsome gingiva together [18-20]. In such cases, the pullingshould be in closed way. In the case reported, due totransposition, the traction was undertaken in open way, as itwas not the case of a simple traction, but rather o correction ofa transposition. Aiming to avoid the gingival recessioncondition, it was realized the positive torque in lower caninein order to diminish inevitable recession [19-22]. Morris et al.[18] concluded that orthodontic treatment is not an importantissue for the development of gingival recession, there was nocorrelation between buccalization of incisors and higherincidence of gingival recession.

ConclusionThe two-plan arch strategy herein demonstrated to be asuitable and efficient solution for the treatment of dentaltransposition in both cases reported. It is indispensable for theorthodontist to have knowledge of different techniques in

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order to optimize the practice and offers biomechanics withminor negative effects.

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