Efficacy and stability of maxillary arch expansion with clear aligners versus conventional slow maxillary expanders in growing patients: A multicenter prospective cohort study

Objective: To compare the efficacy and stability of maxillary arch expansion using clear aligners (CAs) and slow maxillary expanders (SMEs) in growing patients with maxillary transverse deficiency. Methods: This prospective multicenter cohort study included 48 growing patients (mean age, 9.3 ± 1.7 years; CA group: n = 24; SME group: n = 24) requiring maxillary expansion. The maxillary arch dimensions at the crown and gingival levels, arch perimeter, and molar buccolingual inclination were assessed at pretreatment (T0), post-expansion (T1), and post-retention (T2). The primary outcome was intermolar transverse expansion. A predefined non-inferiority analysis was performed to determine whether the expansion achieved with CAs was non-inferior to that achieved with SMEs within a clinically acceptable margin. Secondary analyses assessed the magnitude, pattern, and stability of the expansion through intra-and intergroup comparisons across time points. Results: = 0.26). Significantly greater expansion at the canine cusp tip was observed in the CA group. Age was a negative predictor of expansion at the canine region. Conclusions: Based on a predefined non-inferiority margin, the maxillary arch expansion achieved with CAs was not inferior to that obtained with SMEs in growing patients.