Effect of surface polishing on roughness, biofilm formation, and biocompatibility of 3D-printed denture base resins

3D-printed denture bases may exhibit increased intaglio surface roughness depending on the printing technology, which can favor microbial adhesion and is not always addressed during routine post-processing. This study aimed to investigate the effect of surface polishing on surface roughness and biofilm formation on 3D-printed denture base resins. 3D-printed denture base resin samples were assigned to polished (P) or not polished (NP) groups, with polishing performed using a sequential silicon carbide sandpaper finishing procedure (200–1200 grit). Surface roughness was measured using contact and non-contact profilometers. Topography was analyzed by scanning electron microscopy (SEM), mechanical properties assessed via compressive stress test and water contact angle determined through drop-shape analysis. Biological assays included adhesion and biofilm formation and cytocompatibility with L-929 fibroblasts under direct and indirect contact conditions. Protein adsorption was measured using FITC-BSA. Normality was tested with Shapiro-Wilk and comparisons were performed using Student’s t-test (α = 0.05). The polishing reduced surface roughness from 5.81 ± 0.40 µm to 0.28 ± 0.03 µm, with topographical modifications confirmed via SEM images. Mechanical test showed similar Young’s modulus values for both groups, while polished samples exhibited higher contact angle. Polished surfaces reduced biofilm coverage and metabolism. The procedure demonstrated no cytotoxicity, with fibroblast metabolism consistently at 100% over time. BSA adsorption was comparable between groups. In conclusion, surface polishing reduced surface roughness and biofilm formation on 3D-printed denture base resins without adversely affecting mechanical properties or cytocompatibility.