Surface Properties of Dental Materials Influence the In Vitro Multi-Species Biofilm Formation

This study examined the association between biofilm growth and surface properties of 3D printed, milled, and conventional materials used for manufacturing fixed dental prostheses. Disc-shaped specimens were produced and finished from five 3D-printing resins (VarseoSmile Crown plus [VSC], NextDent C&B MFH [ND], VarseoSmile Temp [VST], Temp PRINT [TP], P Pro Crown & Bridge [P]), two polymer milling blocks (composite: TetricCAD [TC], PMMA: TelioCAD [TEL]), two conventional polymer materials (Tetric EvoCeram [TEC], Protemp 4 [PT]), and zirconia (ZR). Surface roughness (R_a), wettability, interfacial tension (IFT) and surface topography were examined. Three-day biofilms were grown on the specimens using <i>A. naeslundii</i>, <i>S. gordonii</i>, <i>S. mutans</i>, <i>S. oralis</i>, and <i>S. sanguinis</i> in a multi-species suspension. Biofilms were quantified by crystal violet staining and with a plating and culture method (CFU/mL). Linear regression analysis was computed to demonstrate associations between the surface properties and biofilm growth. The strength of this relationship was quantified by calculating Spearman's <i>ρ</i>. TC exhibited the highest, and TP the lowest IFT. TEC showed the highest R_a, while TEL had the lowest, with significant differences detected particularly between milled and 3D-printed specimens. TP specimens exhibited the highest biofilm mass, while ZR surfaces retained the least. Bacterial viability within the biofilms remained similar across all tested materials. There was a strong negative correlation between total IFT and biofilm mass, and a moderate positive correlation between R_a and CFU/mL. Surface properties are shaped by material composition, microstructure, and manufacturing methods and play a crucial role in biofilm formation on dental restorations.