Anti-adherence activity and bactericidal effect of silver-loaded composites

Materials and Methods: Specimens of a resin composite matrix loaded with two different concentrations of a silver additive (Comp0.3: 0.3%; Comp0.6: 0.6%) and one unloaded reference composite matrix (Comp0) were made. Surface roughness was assessed by perthometer measurements and hydrophobicity according to water contact angles was determined by computerized image analysis. The specimens were incubated in a S. mutans suspension (1 h, 37°C) and adhering streptococci were quantified by using a biofluorescence assay. The viability of adhering bacteria was assessed by live/dead cell labeling in combination with fluorescence microscopy.

Results: Statistically significant differences between the median water contact angles of Comp0 (66.3°), Comp0.3 (76.7°), and Comp0.6 (89.4°) were observed. A three- to four-fold higher amount of adhering S. mutans was found on reference Comp0 (12093 relative fluorescence units) than on Comp0.3 (4258 rfu) and Comp0.6 (3292). Significantly higher percentages of dead cells than on Comp0 (0.5%) were found on Comp0.3 (6.1%) and on Comp0.6 (10.1%).

Conclusions: The addition of microparticulate silver to a resin composite material increased the surface hydrophobicity and reduced the number of adhering streptococci. Simultaneously it increased the percentage of dead and inactive cells on the composite surface. Thus, silver additives seem to demonstrate anti-adherence activity as well as a bactericidal effect.