Impact of isopropanol post-washing duration and post-polymerization devices on flexural properties of 3D-printed denture base: An in-vitro study

Purpose: This study evaluated the effects of varying post-washing times and different post-polymerization devices on the flexural properties of a 3D-printed denture base in an in-vitro study. Methods: A total of 48 specimens were printed using one 3D-printing denture base resin (Detax FreePrint Denture) and prepared according to ISO 20795–1:2013. The specimens were divided into two groups based on the independent variables: post-washing duration (6, 12, 90, and 720 ​min) and post-polymerization devices (Otoflash in nitrogen gas [OTN], Otoflash in air [OTA], Otoflash in glycerol [OTG], NextDent LC-3D print box [ND], and a nail salon unit [NS]). Flexural strength and modulus were assessed, and SEM analysis was conducted to examine ductile fracture phenomena. Statistical analysis was performed using one-way ANOVA with Tukey and Bonferroni post hoc tests (α ​= ​0.05). Results: Both post-washing duration and post-polymerizing devices significantly influenced the flexural properties, though all values exceeded ISO standard requirements. Flexural strength for the post-washing duration ranged from 92.28 ​± ​5.56 ​MPa (6 ​min) to 104.81 ​± ​3.71 ​MPa (12 ​min), while flexural modulus varied from 2711.14 ​± ​19.54 ​MPa (720 ​min) to 2962.04 ​± ​83.70 ​MPa (90 ​min). Post-polymerization devices affected flexural strength (83.91 ​± ​2.68 ​MPa for NS to 113.97 ​± ​9.94 ​MPa for ND) and modulus (2320.47 ​± ​115.79 ​MPa for NS to 2997.55 ​± ​87.55 ​MPa for ND). Conclusion: Different isopropanol washing times and post-polymerization devices influenced the flexural properties of the 3D-printed denture base resin, although all results exceeded the ISO standard requirements. A 12-min washing time and the NextDent post-polymerization device produced the highest values. However, it is still recommended that users follow the manufacturer's instructions to ensure optimal and consistent outcomes.