Comparative efficacy of clear aligner mandibular advancement versus traditional functional appliances for skeletal Class II malocclusion: a systematic review and meta-analysis

Clear Aligner Mandibular Advancement (CAMA) has emerged as an esthetic alternative for correcting Class II malocclusion, yet its efficacy compared to traditional functional appliances remains debated. The aim of this systematic review was to systematically evaluate the therapeutic efficacy of CAMA features compared to traditional functional appliances in growing patients with skeletal Class II malocclusion. A systematic search was conducted in PubMed, Embase, Web of Science, and the Cochrane Library up to December 31, 2025. Randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) comparing clear aligners with mandibular advancement against traditional appliances or untreated controls were included. Risk of bias was assessed using RoB 2 and ROBINS-I tools. Treatment effects were synthesized as weighted mean differences (WMDs) with 95% confidence intervals using random- or fixed-effects models based on heterogeneity (I2). Nine studies (1 RCT, 8 NRSIs) comprising 465 participants were included. Meta-analysis revealed no statistically significant differences between CAMA and traditional Twin Block (TB) regarding skeletal angular changes (SNA, SNB, ANB) or vertical dimensions. However, the CAMA group demonstrated a statistically significant, though clinically minimal, greater overjet reduction compared to TB (MD = -0.46 mm, P = 0.03). Notably, CAMA exhibited significantly less lower incisor proclination compared to TB (MD = -0.90°, P = 0.0002). Comparisons with the Herbst appliance showed similar skeletal effects across all dimensions. Based on the currently available evidence, which is predominantly retrospective, CAMA appears to achieve skeletal orthopedic effects comparable to traditional functional appliances in growing Class II patients. The data suggest that CAMA offers superior sagittal dental control, specifically by minimizing unwanted lower incisor proclination. However, given the limited number of high-quality primary studies, these findings should be interpreted with caution and confirmed by future rigorous randomized controlled trials. Registration number: CRD420251050592.