Cytotoxic effect of 3D-printed and thermoformed clear aligner materials on human oral fibroblasts: An in vitro study

Objective To compare the cytotoxicity of three dimensional (3D)-printed resins and conventional materials used for orthodontic aligner production. Methods 3D-printed materials such as 3Dresyn OD-Clear, Clear A, and Tera Harz TC- 85 were compared with one thermoplastic material—Duran+. The samples were stored in artificial saliva at 37°C for 7 and 14 days to simulate the oral conditions during one phase of aligner therapy. The saliva was subsequently diluted with cell culture medium to concentrations of 10% (c1), 20% (c2), and 30% (c3). The cytotoxicity of the materials was assessed in human oral fibroblasts using the CCK-8 assay after incubation periods of 4 hours, 24 hours, 48 hours, and 72 hours. Results Cytotoxic effects were observed for Clear A (62.9% cell viability at c3; 7 days in saliva; 72-hour incubation) and Tera Harz (69.2% cell viability at c3; 14 days in saliva; 72-hour incubation). Significant differences under certain conditions were found between the following material pairs: Clear A and Tera Harz, Clear A and Duran+, 3Dresyn and Clear A, and 3Dresyn and Duran+ (P < 0.05). There were significant differences between the c1 and c3 for specific materials and incubation times (P < 0.05). No significant difference was found between the 7-day and 14-day aligner-wearing protocols (P > 0.05). Conclusions Among the tested materials, 3Dresyn OD-Clear and Duran+ demonstrated consistently good biocompatibility, highlighting their potential for safe clinical use. Although the other materials were generally biocompatible, they exhibited cytotoxic effects under certain conditions, underscoring the need for thorough testing to ensure safe clinical use.