Brand-Specific Differences in the Cytotoxicity of Clear Aligner Materials.

Objective (s): This study aims to evaluate and compare the cytotoxic effects of five commonly used clear aligner brands- ClearCorrect, Invisalign, Spark, SureSmile and Essix PLUS- on various cell lines in order to assess their in vitro cytotoxicity and safety.

Materials and methods: Three cell lines- MRC-5, 3 T3-L1 and Vero- were exposed to the conditioned medium of clear aligner materials. Cytotoxicity was assessed using the MTT assay. The cell cycle, viability, types of cell death and morphological variations were evaluated using flow cytometry and optical microscopy. Descriptive and inferential statistical analyses were performed, applying appropriate tests with a significance level of 5%.

Results: Invisalign and Spark demonstrated the most significant cytotoxic effects, with marked decreases in cell viability and alterations in cell cycle distribution, particularly in Vero cells. Essix PLUS showed reduced cytotoxicity when thermoformed, suggesting that the manufacturing process may influence the material's safety profile. Morphological analysis confirmed that apoptosis and necrosis were the primary mechanisms of cell death.

Conclusion: Clear aligner materials showed varying levels of cytotoxicity, with Invisalign and Spark exhibiting the most pronounced effects, while Essix PLUS demonstrated lower cytotoxicity under certain conditions. These findings highlight the importance of material formulation and manufacturing processes in ensuring safety. Further research is needed to optimise aligner materials for both clinical efficacy and biocompatibility.