Abstract: PURPOSE: To evaluate the mechanical properties and cytotoxicity of a 3D printing polycarbonate material used in digital occlusal splints, and to use this material to manufacture a splint with CAD/CAM technology. METHODS: Specimen of two different materials, 3D printing polycarbonate(PC-plus) and transparent base resin (PMMA) were processed. The flexural strength, elastic modulus, microhardness, hygroscopicity and water-solubility of these materials then were evaluated. According to the standard of GBT16886.5-2003, cell culture and cytotoxicity test in vitro were conducted to evaluate the target materials on the morphology, growth and proliferation of cultured cells (L929). By using 3D printing technology, a splint was made of this 3D printing polycarbonate material. Statistical analysis was performed using SPSS 24.0 software package. RESULTS: For the group of PC-plus, the flexural strength ranged from 89.4 to 109.8 MPa, the elastic modulus from 1939.4 to 2470.9 GPa, the microhardness from 15.6 to 24.7 MPa, hygroscopicity from 2.43 to 11.42 μg/mm³ and water-solubility from 0.11 to 0.30 μg/mm³. For PMMA group, the flexural strength ranged from 75.2 to 88.4 MPa, the elastic modulus from 1349.2 to 2470.2 GPa, the microhardness from 17.5 to 35.3 MPa, hygroscopicity from 12.80 to 16.16 μg/mm³ and water-solubility from 4.74 to 7.44 μg/mm³. The difference between 3D printing PC-plus group and PMMA base resin group was statistically significant (P<0.05). L929 cells showed normal morphology and proliferation increased with culture time. The toxicity grade of all groups was 0-1, and the 3D printing splint was made successfully. CONCLUSIONS: The polycarbonate material for 3D printing has adequate mechanical properties and biocompatibility to meet the requiement of clinical application.

Key words: Three-dimensional printing, Polycarbonate, Occlusal splints, Mechanical properties, Cytotoxicity