Performance of conventional acrylic resin vs. 3D printed resin in surface roughness, hardness, and mechanical resistance

Introduction: Provisional prostheses protect dental preparations during treatment, with conventional and digital methods available for fabrication. While 3D-printed resins show promise for durability and mechanical properties, further research is needed to clarify their advantages over conventional acrylic resins, specifically in terms of surface roughness, hardness, and resistance in provisional crowns. Objective: To compare conventional acrylic resin and 3D printed resin for fabrication of provisional prostheses through an in vitro study on surface roughness, hardness, and mechanical resistance. Material and method: Bars (25 x 12 x 2 mm) of heat-polymerized acrylic resin (RAT=05) and self-polymerized acrylic resin (RAA=05), as well as 3D printed resin (R3D=05), were fabricated for conducting tests on mean surface roughness (Ra), Vickers hardness, and three-point flexural strength. Subsequently, the specimens were evaluated after fracture. Surface characterization was also performed with significant specimens per experimental group (N=1) using a stereomicroscope, scanning electron microscope, and profilometer. Result: Data on surface roughness, hardness, and mechanical resistance were subjected to one-way ANOVA (p < 0.05), followed by Tukey's test when a statistically significant difference was identified. Findings from surface analysis and fractography were presented qualitatively. The R3D group exhibited a surface with successive layers distinct from other resins. There was no statistical difference between groups for surface roughness (p=0.220). However, statistical differences were identified among experimental groups for hardness and mechanical resistance (p=0.000). Notably, the R3D group showed higher mean hardness (19.50 VD) and lower mean mechanical resistance (54.08 MPa). Specimens from the R3D group showed two or more fragments after fracture, whereas other groups exhibited only two fragments. Similarity was observed regarding surface roughness between conventional acrylic resins and 3D printed resin. Conclusion: The 3D printed resin demonstrated both superior and inferior performance compared to conventional acrylic resins in terms of hardness and mechanical strength.