Bisphenol Exposure from Clear Orthodontic Aligners: A Systematic Review of Experimental and Clinical Evidence

Clear orthodontic aligners have become widely adopted in contemporary orthodontic practice; however, concerns persist regarding the potential release of bisphenols from polymer-based materials and their biological effects. This study systematically reviewed the available evidence on bisphenol release from clear aligners, integrating findings from systematic reviews, in vitro investigations, and clinical studies. The literature consistently demonstrated substantial heterogeneity in study design, analytical methods, and outcome reporting. Most in vitro studies reported minimal or undetectable bisphenol A (BPA) release under simulated oral conditions, although isolated investigations identified low levels of leaching, primarily during the initial phase of material exposure. In contrast, clinical studies revealed transient increases in salivary BPA concentrations following aligner placement or attachment procedures, with levels typically returning to baseline within a few days. Emerging evidence also suggests the potential release of alternative compounds, including bisphenol analogues and plasticizers, which may contribute to the overall biological profile of these materials. Despite generally low measured concentrations, the cumulative effects of long-term exposure, particularly in younger populations undergoing prolonged orthodontic treatment, remain insufficiently understood. Overall, current evidence indicates that bisphenol exposure associated with clear aligners is limited and predominantly transient. However, the lack of standardized methodologies and long-term clinical data precludes definitive conclusions regarding their long-term biocompatibility and safety. Future studies should prioritize longitudinal designs, standardized analytical protocols, and comprehensive toxicological assessments.