# The Impact of Clear Aligner Treatment in Masticatory Function and Temporomandibular Disorders: A Clinical Cohort Pilot Study

## TL;DR

This study found that clear aligner treatment temporarily reduces occlusal contact area but does not harm chewing efficiency or cause temporomandibular disorders.

## Contribution

The study is the first to evaluate the relationship between clear aligner treatment, occlusal changes, and masticatory function in a longitudinal cohort.

## Key findings

- Clear aligner treatment temporarily reduces occlusal contact area, which partially recovers after treatment.
- Masticatory performance remains stable after treatment, with no negative impact on chewing efficiency.
- No signs or symptoms of temporomandibular disorders were observed during or after treatment.

## Abstract

Background/Objectives: This study aimed to explore the functional implications of occlusal changes during clear aligner treatment (CAT) to (a) analyze occlusal changes throughout CAT and the extent of post-treatment occlusal recovery; (b) assess the relationship between post-treatment occlusion and masticatory performance; (c) investigate whether case complexity, facial biotype, and type of malocclusion influence occlusal adaptation and functional outcomes; and (d) evaluate the presence and progression of signs or symptoms of TMDs in patients undergoing CAT. Methods: This longitudinal cohort pilot study included 42 individuals who underwent CAT. Occlusion was evaluated at three timepoints: before treatment (T0), at treatment completion (T1), and three months after with night-only aligner use (T2). Masticatory performance was assessed using a two-colored chewing gum test analyzed through colorimetric software. TMD signs/symptoms were assessed using the Diagnostic Criteria for TMD [DC/TMD]. Statistical analysis used non-parametric tests. Results: A significant decrease in occlusal contact area was observed during active CAT [p = 0.016], which partially recovered at follow-up. Individuals with normal facial proportions (normodivergent) showed more anterior contacts at T1 compared to hyperdivergent individuals [p = 0.013]. Masticatory performance remained stable between T1 and T2 [p = 0.528]. A weak negative correlation was found between posterior contact number and performance score at T1 [r = −0.378, p < 0.05], suggesting that more contacts may be linked to better chewing. No TMD signs or symptoms were detected at any timepoint. Conclusions: Although CAT temporarily reduces occlusal contact area, it does not negatively impact chewing efficiency or trigger TMD symptoms. These findings support the functional safety of CAT when treatment is properly planned and monitored.