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S&M Publications Clinical cases Orthodontics Orthodontics Arch contraction and scissor bite: the ideal case to tackle with f22 aligner

Arch contraction and scissor bite: the ideal case to tackle with f22 aligner

Arreghini A.

Arreghini A.

Dr. Angela Arreghini - School of Specialization in Orthodontics, University of Ferrara

Introduction
Orthodontic treatments with transparent aligners are increasingly requested by patients, both adults and adolescents, for their aesthetics and ease of management.
At the beginning of their diffusion, the aligners were dedicated to very simple cases. Today, increasingly complex cases are being treated with this method1, but this can only happen thanks to the help of auxiliaries such as bands, buttons, chains, sectionals or skeletal anchors2, and this can discourage the less experienced doctor.
The F22 Aligners (Sweden & Martina, Due Carrare, Italy) have shown a very high predictability in the movements of buccal-lingual inclination and rotation3, and for this reason they are the treatment of choice in cases of dentoalveolar contraction and cruciate bites of dental origin. They allow to obtain an optimal result with very high precision and in a very short time compared to conventional stationary equipment.
Case report
The patient, age 21, requires aesthetic orthodontic treatment because he is not satisfied with the alignment and width of his smile. Her face is symmetrical, and the profile is convex. The lips are thin but competent. A notable transverse contraction is observed on the smile, the buccal corridors are very accentuated, and this represents the main problem perceived by the patient.
Intraoral analysis shows a first-class molar and canine relationship with moderate crowding, especially in the mandibular arch. The arches are very contracted, the upper and lower premolars are lingualized and there is scissor bite on elements 24-34. In the frontal photo with open mouth the curves of Spee and Wilson appear accentuated.
The latero-lateral teleradiography confirms the first-class normovergent skeletal relationship (ANB = 3°; FMA = 27°) with retroclinated incisors (IMPA = 87°; Upper incisors inclination on the bispinal plane: 103°). The orthopantomography does not show any problems: the mandibular profile is symmetrical, the dental elements are all erupted except for the eighths.
An aesthetic treatment with F22 Aligner was planned, consisting of 20 aligners per arch. Dentoalveolar expansion was planned for the middle and posterior sectors, incisal proclination and a small amount of stripping with the aim of improving the arch shape and recovering space for incisal alignment. The lower incisors were intruded to flatten Spee's curve.
Anchor Grip Points were applied both to the anterior intrusion and to the more complex rotation movements, and on the 21 for the control of the root tip. All the Grip Points in the anterior sector were applied from the lingual side to preserve the aesthetics of the treatment.
The patient was instructed to wear the aligners 22 hours a day and replace the aligners every 15 days. The treatment lasted for 10 months. The patient's cooperation was excellent, as was his satisfaction with the aesthetics of the aligners.
At the end of the aligner sequence, the molar and canine first-class relationship was maintained, and the medians centered. The arches are wide, aligned and coordinated with each other. The planned dentoalveolar expansion was expressed as per virtual setup, in particular the scissor bite of the first premolars of the left side was corrected, and the Spee curve was normalized. On the front photo the smile appears full, the buccal corridors have been reduced.
Discussion and conclusions
Although some very complex movements may require the use of auxiliaries, a wide range of malocclusions can be successfully treated with aligners alone. Among these, dentoalveolar expansion and moderate rotations are the most frequent cases.
The high fitting and precision of the F22 aligners allow a very high expression of the planned movements virtually in the digital setup. The buccal-lingual inclination demonstrated extremely high predictability (3). For this reason, the most complex movement of the case, ie the correction of the scissor bite with a 19° proclination of the element 34, has been completely expressed as virtually programmed, without the need for a subsequent finishing step. The disclusion of the arches during the treatment, due to the posterior thickness of the aligners, has greatly favored the correction of the cross bite, because it eliminated the possible vertical pre-contacts between the premolars, without the need for apply annoying rear lifts.
All these features make the aligners the choice of elections in first class cases with dentoalveolar contraction even of severe degree, dental cross bite and crowding.
Bibliography
1. Lombardo L, Colonna A, Carlucci A, Oliverio T, Siciliani G.. Class II subdivision correction with clear aligners using intermaxilary elastics. Prog Orthod. 2018 Sep 1;19(1):32. doi: 10.1186/s40510-018-0221-5.
2. Lombardo L, Occhiuto G, Paoletto E, Maino BG, Siciliani G. Class II treatment by palatal miniscrew-system appliance: A case report. Angle Orthod. 2019 Mar 12. doi: 10.2319/080218-559.1. [Epub ahead of print]
3. Lombardo L, Arreghini A, Ramina F, Huanca Ghislanzoni LT, Siciliani G. Predictability of orthodontic movement with orthodontic aligners: a retrospective study. Prog Orthod. 2017 Nov 13;18(1):35. doi: 10.1186/s40510-017-0190-0.

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