Optimizing Post-Processing Parameters of 3D-Printed Resin for Surgical Guides

This study evaluated post-processing protocols for 3D-printed implant surgical guides, aiming to determine the ideal timing after printing and post-curing durations that do not compromise residual monomer release and leachable components or mechanical properties. Specimens made of a surgical guide resin were 3D-printed (Formlabs Form 2) into bars (14 × 1 × 1 mm; n = 10) and square-shaped samples (10 × 10 × 1 mm; n = 1). They were grouped based on the time elapsed after printing (immediate, 24 h, and 72 h) and underwent washing in 99% isopropyl alcohol. Post-curing was performed for 5, 10, 20, or 30 min using a UV-light curing unit (NextDent LC-3DPrint Box). Residual monomer and components levels were assessed through solvent dissolution tests (n = 5), while mechanical properties were evaluated via flexural strength (n = 10) and hardness (n = 10). Statistical analysis with one-way ANOVA and Tukey’s post hoc test showed no significant differences in flexural strength across curing times or storage periods (p > 0.05), with values ranging from 42.93 MPa to 59.43 MPa. Monomers and leachable components were significantly higher immediately after printing (0.84 ± 0.36 mm3) compared to other groups (p < 0.05). For Vickers hardness, a 10 min curing protocol produced values comparable to longer durations (20.26 HV at 20 min/24 h), while the lowest hardness was 14.59 HV in the 5 min groups (p < 0.001). These findings suggest that delaying post-processing up to 72 h and reducing curing time to 10 min do not compromise mechanical properties, released monomers, and leachable components.