Investigation of the Effects of Thermal Cycling and Surface Treatments on Interim Resin Materials Produced with Additive Manufacturing

This study aimed to compare the impact of thermal cycling on the flexural strength (σfs) of 3-dimensional (3D) printer resins and polymethyl methacrylate (PMMA). It also aimed to evaluate different surface treatment protocols and surface sealant applications on the surface roughness (Ra) and surface hardness (VHN) of the resins used. Rectangular (25�2�2 mm) and disc (Ø10�2-mm) specimens were fabricated from auto-polymerized PMMA, and 3D-printed resins were tested for mechanical properties (ISO 10477) using thermal cycling (n=10). Disc specimens were separated into three groups (n=10) based on the surface treatments: conventional sanding (C), disk polishing (P), and surface sealant coating (O). Ra and VHN values were statistically analyzed with the Kolmogorov Smirnov, Shapiro Wilk, Independent Samples t-test, Mann-Whitney test, one-way ANOVA test and Kruskal Wallis test (α =.05). A significant main effect was found on the flexural strength analysis for each of the two factors: thermal cycling procedure (p[0.001) and materials (p 0.001). A significant main effect was found on the surface roughness and hardness analysis for each of the two factors: surface treatment protocols (p[0.001) and materials (p[0.001). Based on the results; interim materials produced with 3D-printed resins have better mechanical properties than conventionally polymerized materials. Coated materials had lower surface roughness values than polished ones, and adding a surface sealant agent increased their hardness significantly.