Korean J Orthod. 2021 Mar 25;51(2):135-141. doi: 10.4041/kjod.2021.51.2.135.
OBJECTIVE: To assess the effects of thermoforming on aligner thickness and gap width in six aligner systems with the same nominal thickness.
METHODS: Six passive upper aligners of different brands were adapted to a single printed cast. Each sample was evaluated with high-resolution micro-computed tomography. To investigate aligner thickness and gap width, two-dimensional (2D) analysis was conducted assessing the effects of the following variables: tooth type (central incisor, canine, and first molar), 2D reference points, and aligner type. Data were analyzed and compared using analysis of variance and Tukey’s post-hoc tests (p < 0.05).
RESULTS: Tooth type, dental region, and aligner type affected both the gap width and aligner thickness. The aligner thickness remained moderately stable across the arch only in the F22.
CONCLUSIONS: All thermoformed samples displayed smaller aligner thickness and gap width at anterior teeth and both gingival and coronal centers than at posterior teeth and occlusal surfaces.