Material Influence on Retention Characteristics of Orthodontic Aligners—A Systematic Review

Clear aligners are increasingly preferred for their aesthetics and convenience, particularly amongst adults. This systematic review aims to highlight the effect of various materials of aligners on aligner retention. An electronic search was made up to March 2025 using different databases, which include: LILACS, Cochrane, MEDLINE (via PUBMED). Four independent reviewers conducted the study selection, data extraction and risk of bias evaluation. The quality of the included studies was assessed using the JBI tool. Eligibility criteria include peer-reviewed prospective and retrospective clinical studies, including randomised trials, cohort and case-control studies. Results were analysed by evaluating various relevant parameters: retention efficacy, measured via fit, resistance to dislodgement and material adaptation over time. Amongst 343 articles, six were finally selected after full text reading and risk assessment. Literature shows that the retention in aligner therapy is primarily influenced by material properties such as modulus of elasticity, fatigue resistance, and structural behaviour rather than thickness alone. High-modulus materials like TC-85 and BENQ PET offer superior retention and force control, making them ideal for complex tooth movements. Aligner retention is primarily influenced by material properties such as modulus, elasticity, and fatigue resistance, with high-modulus materials like TC-85 and BENQ PET offering the most consistent and effective performance.