Predictability of Microbial Adhesion to Dental Materials by Roughness Parameters

Microbial adhesion to intraoral biomaterials is associated with surface roughness. For the prevention of oral pathologies, smooth surfaces with little biofilm formation are required. Ideally, appropriate roughness parameters make microbial adhesion predictable. Although a multitude of parameters are available, surface roughness is commonly described by the arithmetical mean roughness value (Ra). The present study investigates whether Ra is the most appropriate roughness parameter in terms of prediction for microbial adhesion to dental biomaterials. After four surface roughness modifications using standardized polishing protocols, zirconia, polymethylmethacrylate, polyetheretherketone, and titanium alloy specimens were characterized by Ra as well as 17 other parameters using confocal microscopy. Specimens of the tested materials were colonized by C. albicans or S. sanguinis for 2 h; the adhesion was measured via luminescence assays and correlated with the roughness parameters. The adhesion of C. albicans showed a tendency to increase with increasing the surface roughness—the adhesion of S. sanguinis showed no such tendency. Although Sa, that is, the arithmetical mean deviation of surface roughness, and Rdc, that is, the profile section height between two material ratios, showed higher correlations with the microbial adhesion than Ra, these differences were not significant. Within the limitations of this in-vitro study, we conclude that Ra is a sufficient roughness parameter in terms of prediction for initial microbial adhesion to dental biomaterials with polished surfaces.