The influence of the segmented T-loop anteroposterior position on the initial retraction movement: an evaluation by means of the finite element method

Raquel Silva LOTTI, Enio Tonani MAZZIEIRO, Janes LANDRE JÚNIOR

Aim: this study evaluated the effect produced by segmented stainless steel T-loop in different positions between a canine and a first lower molar on the force system by the FEM (Finite Element Method). Methods: the type of movement of each anchorage units and the stress found in the alveolar bone were assessed in each T-loop positions. The loop was made without preactivations bends. The posterior segment of the left side of the mandible, a canine, second premolar and first molar was modelated. There were obtained 3 different T-loop positions: close to the canine, close to the molar and in a centered position. The initial displacement of those teeth and relative differences between them were evaluated in qualitative terms. Results and Conclusions: when the tooth was close to the loop its displacement and inclination was smaller. An extrusive component of force was presented in all models, however it was smaller for the tooth far away from the loop. Displacements of those teeth to the lingual and buccal sides were observed as a result of relative rotation. This effect was more evident when the tooth was far from the loop. The canine displacement was more significant than the molar in all models. The stress analysis on the alveolar bone indicated higher levels around the canine and when the loop was close to the molar.

Keywords: Biomechanics. Orthodontics. Space closure.

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