# In Vitro Mechanical Study of Three-Dimensional Printed Invisible Dental Aligners for Crowded Dentition Problems: A Patient-Specific Study

## TL;DR

This study tests how 3D-printed dental aligners of different thicknesses perform under pressure, focusing on their mechanical behavior for crowded teeth.

## Contribution

The study explores optimal shell thickness for 3D-printed dental aligners using patient-specific models and mechanical testing.

## Key findings

- No significant differences in compressive extension were found among the four thickness groups.
- The 0.08 mm thickness showed lower compressive extension, but the result was not statistically significant.
- The study highlights limitations and suggests directions for future research on 3D-printed aligners.

## Abstract

Clear aligners are a popular alternative to fixed orthodontic appliances; however, technical data on the optimal final aligner shell thickness for directly printed aligners remain limited. This in vitro experimental pilot study evaluated the mechanical response of patient-specific, directly 3D-printed aligners of four nominal shell thicknesses (0.04, 0.06, 0.08, and 0.10 mm) fabricated from BioMed Clear resin. A single subject with dental crowding was scanned and a set of aligner shells was designed and printed (n = 3 per thickness). Compressive tests up to 1000 N were performed and compressive extension (mm) recorded; group means ± SD were compared by means of one-way ANOVA. No statistically significant differences in compressive extension were found among the four thickness groups (ANOVA, F(3,8) = 2.242, p = 0.161). The 0.08 mm group showed a lower mean compressive extension in this dataset, but the difference did not reach statistical significance; given the small sample size and single-subject nature of the study, this result should be considered exploratory. This recent study clarifies printing and post-processing parameters and highlights limitations and directions for future work.