Influence of different printing orientations and post‐polymerization time on the translucency of three‐dimensional (3D) printed denture base resins

Abstract Purpose To evaluate the effect of different printing orientations and post‐polymerization time with thermal cycling on the translucency of 3D‐printed denture base resins. Methods Heat‐polymerized (HP) acrylic resin specimens were fabricated and 3D‐printed denture base materials (NextDent, ASIGA, FormLabs) were printed with different printing orientations (0, 45, 90 degrees) and subjected to different post‐polymerization times (15‐, 30‐, 60‐, and 90‐min). All specimens were polished and immersed in distilled water for 1 day at 37°C. CIEDE2000 was used to measure the translucency parameters (TP 00 ) before and after thermal cycling (5000 cycles) recording the color parameters (L * , a * , b * ) against a black and white background using a spectrophotometer. k ‐factors ANOVA followed by post hoc Tukey's test (α = .05) was performed for statistical analysis. Results The k ‐factors ANOVA test showed a significant effect of resin material, post‐polymerization time, and printing orientation on translucency ( p < 0.001). In comparison to HP, all 3D‐printed resins showed lower translucency with all post‐polymerization times and printing orientation ( p < 0.001) except FormLabs resin ( p > 0.05). For all 3D‐printed resins, the translucency increased, with increasing the post‐polymerization time ( p < 0.001) and 60‐ and 90‐min showed the highest translucency. For printing orientation, 90 and 45 degrees significantly showed high translucency in comparison to 0 degrees ( p < 0.001). FormLabs showed significantly higher translucency when compared with NextDent and ASIGA per respective printing orientation and post‐polymerization time. The translucency significantly decreased after thermal cycling for all tested resins ( p < 0.001). Conclusion The findings of this study demonstrated that the translucency of 3D‐printed resins is influenced by the printing orientation, post‐polymerization time, and resin type. As a result, choosing a resin type, and printing orientation, with a longer post‐polymerization time should be considered since it may improve the esthetic appearance of the 3D‐printed resins.