Mechanical performance and biocompatibility of denture base resins fabricated by direct light processing under...

Optimizing post-polymerization atmospheres is critical for improving the clinical performance and durability of DLP-printed denture base resins. This study evaluated the effects of post-polymerization atmospheres and thermal aging on the mechanical, physical, and biological properties of denture base resins fabricated by digital light processing (DLP). A milled denture base resin served as the control (M), and DLP-printed specimens were post-polymerized under three atmospheric conditions: air (A), vacuum (V), and nitrogen (N). Vickers hardness, flexural strength, and flexural modulus were evaluated before and after thermal aging, while polymerization efficiency and cytocompatibility were further analyzed. Statistical analysis was performed using one-way analysis of variance (ANOVA), with the significance level set at P < 0.05. The M group consistently exhibited superior mechanical properties and aging stability, with flexural strength decreasing from 110.92 ± 5.01 to 104.40 ± 1.79 MPa and Vickers hardness from 21.41 ± 0.65 to 19.31 ± 0.28 VHN after aging. Among the DLP groups, the A group showed higher flexural strength and hardness, decreasing from 95.78 ± 1.45 to 83.63 ± 3.73 MPa and from 19.96 ± 1.55 to 12.67 ± 1.83 VHN, respectively. Thermal aging significantly reduced flexural strength, flexural modulus, and hardness in all groups (P < 0.05). However, all DLP groups showed acceptable degree of conversion and cytocompatibility, with relative cell viability exceeding 70% and meeting ISO 10993-5 requirements. Therefore, optimization of post-polymerization conditions is essential to improve long-term clinical performance without compromising biological safety.