Related Experiment Video
Updated: May 28, 2026
Measuring Maxillary Posterior Tooth Movement: A Model Assessment using Palatal and Dental Superimposition
Published on: February 23, 2024
Micro-CT evaluation of aligner fit and thickness in 3D-printed and thermoformed aligners: Differences in relation to
1Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea.
Objective:
To assess the adaptation and thickness of three-dimensional (3D)-printed and thermoformed aligners, comparing differences in relation to fabrication methods, inner-surface offset, and tooth region.
Methods:
Thirty maxillary aligners were fabricated: 3D-printed aligners (0.5 mm) with no offset (n = 10) or a 0.05-mm offset (n = 10) and thermoformed aligners from 0.75-mm sheets (n = 10). All aligners were fitted onto a dental model and scanned using micro-computed tomography. Gap distance and thickness were measured at five anterior and seven posterior tooth regions. Thickness ratios after fabrication were calculated. Group and tooth-region differences were analyzed using oneway analysis of variance with Tukey's post hoc test, or Kruskal-Wallis and Mann-Whitney U tests.
Results:
The no-offset 3D-printed aligners showed larger gaps (0.07-0.15 mm) than the 0.05-mm offset and thermoformed aligners (0.05-0.09 mm). Thickness was greater in 3D-printed aligners (0.68-1.08 mm) than in thermoformed aligners (0.47-0.70 mm). Thickness ratios exceeded 100% in 3D-printed aligners, particularly at the cervical and central fossa regions, whereas thermoformed aligners showed thinning (< 100%), most notably at the labio/buccocervical areas. In comparisons based on tooth region, no-offset 3D-printed aligners showed greater gaps at the buccal, buccocervical, central fossa, and palatal cusp tip regions (P < 0.001), whereas the 0.05-mm offset group exhibited no significant differences. Thermoformed aligners showed larger gaps at the palatocervical, palatal, and palatal cusp tip regions of posterior teeth (P < 0.001).
Conclusions:
A 0.05-mm offset in 3D-printed aligners produced gap values comparable to those obtained with thermoformed aligners and showed consistent adaptation over tooth regions. 3D-printed aligners tended to show greater thickness than their virtual design, whereas thermoformed aligners showed reduced thickness.
