In Vitro Cytotoxicity Assessment of Different Thermoplastic Aligner Materials

This study evaluated the cytotoxicity of different thermoplastic materials and the impact of thermoforming on their cytotoxicity.

Four 3D thermoplastic materials were tested before and after thermoforming: Zendura A (Bay Materials), Zendura FLX (Bay Materials), Erkoloc-pro (Erkodent), and CA Pro + (Scheu Dental). The samples were stored in artificial saliva and incubated at 37 °C for 14 days to simulate conditions in the oral cavity during one stage of clear aligner treatment. Then, the saliva was diluted with a complete culture medium at three concentrations: c1=10%, c2=20% and c3=30%. Cytotoxic activities of the materials were evaluated after incubation for 4h, 24h, 48h, and 72h by using the CCK-8 assay on human oral fibroblast cells (Innoprot, REF: P10868).

The mean measured values of metabolically active cells below 70% of the control were for c3 of non-thermoformed Zendura A and Erkoloc-pro, and thermoformed Zendura A, after 72-hour incubation. The analysis showed differences between non-thermoformed: Zendura A and Erkoloc-pro and Zendura FLX and CA Pro +, thermoformed: Zendura A and CA Pro +, and Zendura FLX and CA Pro + at certain conditions. Differences between concentrations (c2 vs. c3 and c1 vs. c3) in the non-thermoformed group were found. There were no statistically significant differences in cytotoxicity between non-thermoformed and thermoformed groups.

Cytotoxicity was observed in non-thermoformed and thermoformed materials, with significant differences between concentrations of the same material. However, the thermoforming process did not impact the cytotoxicity of clear aligner materials.