Dietary changes in patients with clear aligners compared with fixed orthodontic appliances during the early stages of orthodontic treatment: A systematic review.

Objective: This systematic review evaluated dietary changes during the first 6 months of orthodontic treatment between multibracket fixed appliances and clear aligners. Methods: Five databases (PubMed, Web of Science, Cochrane's Database of Systematic Reviews, EMBASE, Scopus) were searched through January 2025 for longitudinal studies on healthy participants undergoing non-extractive orthodontic treatment with multibracket fixed appliances or clear aligners, assessing dietary changes. Data on diet change were extracted at baseline, 24 hours, 1 week, 2 weeks, 1-2 months, and 3-6 months, and descriptively compared with pain outcomes. Quality assessment was performed using Risk-of-Bias-2.0 and ROBINS-I; overall certainty of evidence was evaluated with GRADE. Results: The search retrieved 180 studies; 56 were screened, and 22 full-text articles were reviewed. Nine studies (671 participants, 58.9% females) were included. Despite no significant baseline differences between groups, 24 hours after appliance placement, all studies indicated significantly greater diet-related limitations in the multibracket group than in the aligner group, with differences of 0.1-0.9 points on a 0-10 scale. Trends persisted at 1 week (differences 0.7-1.8 points), 2 weeks (0.8-1.9 points), 1-2 months (0.1-2.0 points), and 3-6 months (0.8-3.0 points). Across timepoints, comparisons of pain intensity and dietary changes did not reveal consistent patterns. Conclusions: During the first 6 months, multibracket appliances may affect diet more negatively than clear aligners and this pattern does not seem to be explained by differences in pain. Given the low-to-moderate certainty of evidence and indirect diet assessment using items from broader oral health-related quality of life instruments, these results should be interpreted with caution.