Evaluation of the dental arches shape influence in the anterior crowding relapse

• Autor(a) principal: Tkacz, Caroline Martins Gambardela
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/25/25144/tde-22102021-111306/
• topic: Arco Dental; Dental Arch; Extração Dentária; Longitudinal Studies; Má Oclusão; Malocclusion; Recidiva; Recurrence; Tooth Extraction

Aim: To compare changes in linear transversal dimensions and dental arch shape during at pretreatment, posttreatment and in long-term according to the severity of anterior crowding in individuals treated with 4-premolars extraction. Material and Methods: The sample consisted of 41subjects with Class I and II sagittal relationship treated with extraction of 4 premolars, divided into 2 groups according to the severity of the anterior crowding and evaluated in the pretreatment, posttreatment and postretention. Group Mild crowding: subjects with initial mandibular Little irregularity index (LII) less than 6mm Group Severe crowding: subjects with initial mandibular Little irregularity index of 6mm or greater. Three-dimensional images of dental casts were analyzed. Little\'s irregularity index, the transverse and longitudinal widths of the maxillary and mandibular arches were evaluated. Intergroup comparisons were performed with independent t tests. The anatomical landmarks were marked, the x, y, z coordinates for each landmark were collected for maxillary and mandibular arches. Generalized Procrustes Analysis, Principal Component Analysis and Canonical Variates Analysis were used to examine the variation between individuals and groups. Results: The groups presented similar behavior between them for maxillary and mandibular arches dimensions and dental crowding for all stages. The variables showed different behavior among the stages in both groups. The Principal Components Analysis demonstrated greatest variation in the shape was related to the displacement of the incisor and canines. The arch shape changed with treatment and was maintained, with slight variation, over the long-term follow-up. The behavior for maxillary either mandibular dental arches for both groups were similar. Conclusion: There were no differences between mild and severe crowding groups for dental arch dimensions, but the mild group presented greater mandibular percentage of relapse. The initial dental arch shape was modified during the treatment and showed slight variation in the long-term follow-up in both groups.