PROPRIETA' STRUTTURALI E RILASCIO DEI BISFENOLI DURANTE L'INVECCHIAMENTO DEGLI ALLINEATORI ORTODONTICI

The widespread use of clear aligners in orthodontic treatment has increased intraoral exposure to polymer-based devices, raising concerns about their chemical stability and biological safety. Orthodontic aligners are subjected to several stresses within the oral cavity, thereby increasing the risk of degradation and the potential release of endocrine-disrupting compounds. The current scientific literature is limited and mainly focuses on bisphenol A, neglecting the wider effects of related substances and their mixtures. Therefore, this study aimed to directly compare the chemical and biological safety of modern clear aligner materials through a combined experimental approach. Commercial polymers and 3D-printed resins underwent standardised in vitro ageing in solvents that mimicked various intraoral conditions. The resulting solutions were analysed using Fourier Transform-Infrared Spectroscopy (FT-IR) and Gas Chromatography-Mass Spectrometry (GC-MS). Additionally, extracts were examined for estrogen-like biological activity with an MCF-7 cell proliferation assay to detect effects not identified by the analytical techniques. The results showed that ageing, chemical release, and biological effects varied depending on the material. Chemical analysis did not identify specific compounds, such as bisphenol A or related chemicals. These findings were supported by biological assays, which found no estrogenic activity. This study provided a clear, clinically relevant assessment of the safety of orthodontic clear aligner materials, demonstrating that combining analytical and biological testing enhances risk assessment, supports evidence-based clinical decisions, and guides future advances in clear aligner therapy.