Evaluation of Clear aligners initial adaptational fit for different orthodontic movements

• Ano de defesa: 2024
• Autor(a) principal: Silva, Vinicius Augustus Merino da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Alinhadores estéticos; Aparelho ortodôntico; Clear aligner therapy; Dental models; Imagem; Imaging; Modelo dentário; Orthodontic appliance; Three-dimensional; Tridimensional
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/25/25144/tde-03092024-094353/

Introduction: Clear aligners initial misfit has a major impact on the accuracy of the orthodontic movement. The objective of this study was to evaluate a new method to analyze the initial misfit of clear aligners in the attachments using different degrees of activation during the extrusion and mesialization movements of the upper central incisors. Methods: This study comprised two groups: Group Extrusion (GE) simulated the extrusion of the left upper central incisor using a horizontal semicircular attachment. Group Mesialization (GM) simulated a bodily mesial movement of the right upper central incisor using a vertical semicircular attachment. In each group, five 0.8-mm clear aligners were thermoformed for three activations: passive, 0.1mm correction, and 0.2mm correction. All 15 aligners per group were sequentially adapted in a printed dental model presenting a malocclusion of 0.5mm intrusion in GE and a 0.5mm midline diastema in GM. High-resolution cone-beam computed tomography (CBCT) exams were acquired for each positioned clear aligner. Axial sections and cross sections were reconstructed using 3D slicer software (www.slicer.org). Linear measurements from the attachments/incisor labial aspect to the inner surface of the aligners were performed in the target and adjacent teeth by two previously calibrated evaluators. Intra and inter-examiner reproducibility was evaluated using intraclass correlation coefficient (ICC) and Bland-Altman (p<0.05). The comparison between different activations was performed with MANOVA test and Tukey or Kruskal Wallis tests (p<0.05). Results: : Intra-examiner measurements demonstrated excellent or good agreement for all variables (ICC ranging from 0.723 to 0.983). The linear measurements at the attachment ramp showed the greatest limits of agreement in GM (-0.077 and 0.093). Inter-examiner reproducibility was excellent (ICC ranging from 0.817 to 0.992). The linear measurements at the edge of the attachment showed the greatest limits of agreement in GE (-0.098 and 0.154). In GE, an increase in the clear aligner misfit was observed between passive, 0.1 and 0.2mm of activation in the attachment region of target central incisor. No difference in the aligner misfit was observed between activations in the neighbouring teeth. In GM, the amount of misfit in the attachment and labial surface of target central incisor was greater for 0.2mm activation compared to both passive and 0.1-activated aligners. The contralateral central incisor showed an aligner misfit in the mesial third of the labial aspect. Conclusion: The new method of evaluation of clear aligner misfit showed adequate reliability for both horizontal and vertical movements. The initial maladjustment of the aesthetic aligners increased as activations increased. Upon extrusion, aligner incompatibility was only observed in the target teeth. Clear aligners initial misfit increased with greater activations. In extrusion, the aligner mismatch was observed only in the target teeth. On the other hand, in the mesial movement the aligner mismatch was noticed both in the target and contralateral tooth.