Effect of surface polishing on roughness, biofilm formation, and biocompatibility of LCD-printed denture base polymer

This study investigated the effect of surface polishing on roughness, mechanical performance, and biological properties of a liquid crystal display (LCD)-printed denture base polymer. Disc-shaped samples of three-dimensional (3D) printing polymer were fabricated and allocated to polished (P) or not polished (NP) groups for comparative analysis. Polishing was performed manually in a standardized manner using sequential silicon carbide sandpapers, while the NP samples were sanded to reproduce the texture generated by the printing lines. Surface roughness was measured by contact and non-contact profilometry, and topography analyzed by scanning electron microscopy (SEM). Mechanical properties were assessed by compressive stress testing and wettability by water contact angle. Biological assays included C. albicans biofilm proliferation (colony-forming units, CFU), metabolism (Alamar blue assay) and coverage (Live/Dead). Cytotoxicity tests with L-929 fibroblasts under direct and indirect contact were also performed. Protein adsorption was evaluated using Alexa Fluor 488-labeled Bovine Serum Albumin (BSA). Data were analyzed with Student's t-test (alpha = 0.05). Polishing significantly reduced roughness to the clinically acceptable threshold, with SEM and laser microscopy confirming reduction of irregularities. Mechanical testing showed similar Young's modulus values between groups, while polished samples exhibited higher contact angles. Polished surfaces reduced C. albicans biofilm metabolism and coverage on the samples, although CFU counts did not differ significantly. Cytotoxicity tests demonstrated cell metabolism comparable to the control group (100% viable cells) over time. Protein adsorption was equivalent between groups. In conclusion, polishing reduced surface roughness and C. albicans metabolism and coverage on LCD-printed denture base, while maintaining mechanical properties and cytocompatibility.