A 58-year-old patient presented molar and canine Class II relationships on both sides (Figure 1). Maxillary and mandibular interincisal midlines did not coincide. Clinical intraoral examination showed the maxillary arch quite aligned, with mild rotations of the left incisors. On the other hand, the mandibular arch presented a multibraided fixed retainer bonded to all six anterior teeth with the right canine root lingually torqued. The root was exposed, almost revealing the apex, and the element was not vital. Elements 3.2 and 3.3 resulted retroclined, withdiastemas between elements 3.1-3.2 and 3.2-3.3, a 90  rotation of 3.3. Calculus in the fifth sextant, multiple recessions, and restorations were present.
A cone-beam computed tomography (Orthophos SL 3D, Sirona, Bensheim, Germany) was performed, confirming the former periodontal findings (Figure 2(a)). The root of the right canine was not covered by cortical bone anymore (Figures 2(b) and 2(c)).
Clinicians suggested different solutions to the patient. The first alternative involved the extraction of all lower incisors and the right canine, followed by the placement of dental implants with guided surgery and, finally, a prosthetic rehabilitation. However, this alternative would have not solved the rotation of element 3.3. The second alternative considered every other prosthetic solution without implant placement, but it would have led to treatment failure as extracting lower cuspids would have meant removing the anchor teeth or pillars for the prosthetic rehabilitation. These alternatives were too invasive and radical, in particular, the former alternative could have led to failures and peri-implantitis.
The most conservative solution was fixed orthodontic treatment with multibracket appliance aiming at preserving the affected teeth. This option was the least invasive, but it could have been complex from a biomechanical point of view and challenging for the retrieval of the right canine, with poor prognosis. Consequently, after being informed of all risks and having signed an informed consent, the patient chose to undergo orthodontic treatment only for the lower arch.
The primary objective was to correctly reposition the mandibular right canine, in order to avoid the placement of a dental implant or fixed dental bridge. As the patient requested a noninvasive treatment, it was decided to start fixed orthodontic treatment only on the lower arch.
After the removal of the fixed retainer, periodontal probing, supra and subgingival professional oral hygiene was performed. Periodontal probing and supragingival oral hygiene sessions were repeated if needed for calculus accumulations during all orthodontic treatment. A multibracket treatment was performed with the MTB technique. Brackets (3M Unitek, Monrovia, CA, USA) were bonded from elements 3.5 to 4.5, and molar bands with double tubes (3M Unitek) were cemented to elements 3.6 and 4.6. On the lingual side of molar bands, Wilson 3D lingual tubes (Rocky Mountain Orthodontics, Denver, USA) with vertical insertion were welded. In order to obtain additional torque on the right mandibular canine, a lower second premolar bracket (3M Unitek) was bonded. A 0.012-in NiTi archwire 3M (Figure 3) was ligated. A Wilson 3D sectional archwire (Rocky Mountain Orthodontics) was inserted on element 4.6 (Figures 4(a) and 4(b)) as an additional lingual/apical force became necessary to help the root apex return in the alveolar bone base. Its mesial extremity was placed on the most apical point of the root of the right canine, distant from lingual mucosa. The lingual sectional was removed after three months of treatment. Meanwhile, the following arch sequence was used: 0.014-in NiTi (Figure 5), 0.016-in NiTi, and a 0.019 x 0.025-in NiTi (3M Unitek). Light archwires were used for a long time in order to achieve a good alignment; considering the age of the patient, continuous and light forces were exerted to respect periodontal tissues. Subsequently, a 0.019 x 0.025-in TMA (3M Unitek) was used. Additional torque was progressively added on the right canine for the next three months. Treatment continued with the addition of radicular-vestibular torque on the IV quadrant and an elastic chain (3M Unitek) applied to close spaces.
The multibracket treatment lasted a year and a half. The mandibular right canine was repositioned (Figure 6) and a periodontal examination showed probing pocket depth values of 3 mm. In addition, the general dentist decided to perform root canal treatment of the canine one year after the beginning of orthodontic treatment as the tooth was not vital and not symptomatic. Elements 3.2 and 3.3 were repositioned too, and spaces were closed (Figure 7).
A spring retainer was delivered to the patient (Figure 8). It consisted of an anterior stainless-steel wire with vestibular and lingual resin components. The latter extended to the molars to improve stability.
The patient was visited after 1, 5, 12, and 18 months from the end of the orthodontic treatment. The stability of the results was observed after 18 months (Figure 9). The patient was satisfied by the result of the therapy but was aware that unwanted tooth movement could occur in the upper arch anyway as she excluded every kind of retention. The patient will continue to be under close observation through regular follow-up examinations.