The mechanical effect of aligner’s thickness and material properties in invisible orthodontics: A quantitative finite element study

Abstract

Invisible orthodontics benefits significantly from aligner technology, yet optimizing material properties and thickness for diverse patient needs is a challenge. The aim of this study was to investigate the interaction between key material properties and thickness—and their collective influence on orthodontic treatment outcomes. A three-dimensional model of the tooth, periodontal ligament, and bone complex was constructed, with attachments centered on each tooth crown. Nine aligners, varying in thickness from 0.20 to 1.00 mm with material properties (Young’s modulus (E) from 0.01 to 3.50 GPa and Poisson’s ratio (ν) at 0.30), were analyzed. The study measured force and moment changes due to a 0.15 mm mesial-distal movement of the lateral incisor, validated by other teeth. Results show aligner thickness and E significantly affect force and moment, with increases promoting translational rather than tipping movements. These findings underscore precise aligner design’s role in enhancing orthodontic outcomes.