Effectiveness and biomechanical predictability of contemporary clear aligner therapy in deep-bite correction: a systematic review and meta-analysis

Purpose Clear aligner therapy (CAT) is increasingly used for deep-bite malocclusion; however, its effectiveness and biomechanical predictability remain unclear. This systematic review and meta-analysis quantified overbite reduction and its contributing mechanisms in contemporary CAT.Methods Databases (PubMed, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar) were searched from inception to 1 December 2025. Eligible studies were retrospective or prospective clinical trials reporting pre- to post-treatment overbite (mm) with SDs in non-extraction dual-arch CAT (Invisalign) for deep bites. The risk of bias was assessed using ROBINS-I and certainty was assessed using GRADE. Random-effects meta-analysis pooled the means/SDs for overbite, incisor intrusion, molar extrusion, and mandibular plane angle. Heterogeneity was quantified using I2 and prediction intervals.Results Six retrospective studies (n = 177 patients; mean age 24.5–40 years) were included, all of which had a moderate risk of bias. Pooled overbite reduction was 1.79 mm (95% CI 1.03–2.54; I2 = 96.3%; prediction interval −0.78 to 4.36 mm). Primary mechanisms: lower incisor intrusion 1.37 mm (95% CI 0.59–2.14; I2 = 86.1%), lower molar extrusion 0.70 mm (95% CI 0.38–1.03; I2 = 58.1%), upper incisor intrusion 0.53 mm (95% CI 0.17–0.90; I2 ≈78%), upper molar extrusion 0.32 mm (95% CI 0.08–0.56; I2 = 37.7%), and mandibular plane opening +0.54° (95% CI 0.33–0.74; I2 = 0%).Conclusions CAT achieves modest dentoalveolar deep-bite correction, with high variability and limited refinement efficacy. It suits mild-to-moderate cases but underperforms fixed appliances for severe deep bites; hybrid approaches are recommended.