Effect of three different attachment designs in the extrusive forces generated by thermoplastic aligners in the maxillary central incisor

Rafael COSTA, Fernanda Calabró CALHEIROS, Rafael Yagüe BALLESTER, Flávia GONÇALVES

Introduction: Orthodontic aligners use have increased in dentistry. The resolution of complex movements such as extrusion demands the use of attachments to reach the aimed force, but just a few studies have been developed to evaluate the biomechanical performance of the aligners and their accessories. Objective: The objective of this study was to evaluate on the three axes (X, Y and Z) the forces generated by three different attachment designs for the extrusion of the maxillary central incisor using esthetic orthodontic aligners. Methods: Three prototypes of maxillary models were developed, each one with a specific attachment inserted in the central incisor. Three aligners were manufactured for each of the three attachment designs, with 0.33-mm activation in the direction of the extrusion. An analytical device was used to evaluate the forces applied to the three axes by each aligner/attachment. The data were assessed by one-way ANOVA and Tukey’s test (α = 0.05). Results: All of the studied attachment designs could satisfactorily perform the extrusion movement. However, force intensities were different in the three designs (design 1 = 2.5 N; design 2 = 2.2 N, and design 3 = 1.1 N). Furthermore, two of the three attachment designs (designs 1 and 2) eventually exerted significant forces on the X (mesiodistal) and Y (buccopalatal) axes. Conclusion: The attachment design 3 presents the best distribution of forces for extrusion movement, generating almost null forces on X and Y axes, and lower intensity of force on the Z axis.

Keywords: Orthodontic extrusion. Orthodontic appliances. Biomedical technology.

How to cite: Costa R, Calheiros FC, Ballester RY, Gonçalves F. Comparison of three different designs of attachments in the extrusive forces generated by thermoplastic aligners in the upper central incisor. Dental Press J Orthod. 2020 May-June;25(3):46-53. DOI: https://doi.org/10.1590/2177-6709.25.3.046-053.oar

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