Biofilm formation of mixed Candida albicans and methicillin-sensitive Staphylococcus aureus and surface properties of a 3D-printed denture base resin under different printing parameters.

Abstract

Objective: To evaluate the formation of mixed-species biofilms of Candida albicans and methicillin-sensitive Staphylococcus aureus (MSSA) on the surface of a 3D-printed denture base resin, as well as its surface properties, under varying printing parameters.

Methodology: Discs (n=40 per group, 10×1.2 mm) of a denture base resin (priZma 3D Bio Denture) were fabricated using two 3D-printers-Liquid Crystal Display (LCD) and Digital Light Processing (DLP)-at three different angles (0°, 45°, or 90°). Surface roughness was measured using a digital profilometer and expressed as Ra (µm). For surface energy (SE) analysis, contact angles were measured using a tensiometer. Discs were incubated at 37 °C for 90 minutes and 48 hours to enable biofilm formation using C. albicans and MSSA inocula. Cell viability was assessed by colony-forming unit (CFU/mL) counts, and metabolic activity was evaluated using the XTT assay (absorbance). Microbial counts and XTT results were analyzed by three-way ANOVA (printer type, printing angle, incubation period). Surface roughness was analyzed by two-way ANOVA (printer type, printing angle), with Tukey's test and a significance level of 0.05.

Results: For both CFU/mL and XTT assays, incubation period was the only significant factor (p<0.001 and p=0.006, respectively), while other factors and interactions were not statistically significant (p>0.05). Surface roughness was significantly influenced by printer type, printing angle, and their interaction (p=0.027). The LCD 0° and LCD 90° groups produced smoother surfaces compared with LCD 45° (p=0.002), which showed similar values to all DLP groups regardless of angle (p>0.05). The DLP printer did not show significant roughness variations across the tested angles (p>0.05). The LCD groups presented numerically lower SE values compared to the DLP groups.

Conclusion: The LCD system performs better than DLP in reducing surface roughness at 0° and 90°. Moreover, the analyzed factors did not significantly affect microbial adhesion or the formation of mixed-species biofilms.