Microbial contamination and inhibitory effect against Streptococcus mutans from fifth-generation bonding systems.

PURPOSE The aim of this study was to evaluate microbial contamination and inhibitory effect against Streptococcus mutans (SM) of Prime & Bond (PB), Single Bond (SB) and Excite (EX) bonding systems before use, and after 10 and 20 applications. METHODS The bonding material was collected by applying a drop of the material directly on broth brain-heart infusion. The samples were homogenized, diluted and seeded on blood agar plates. To evaluate the inhibitory effect on SM, a drop of each bonding material was dispensed on filter discs and placed on blood agar plates. The Cochran statistical analysis was used to evaluate the total amount of viable bacteria among the different bonding systems. Comparisons between the inhibitory effects on SM were made using the Kruskal-Wallis test. RESULTS Adhesives SB and EX presented microbial contamination (p<0.05) and inhibitory effect (p<0.05) over SM strains with statistically significant differences concerning PB. SB and EX inhibitory capacity remained after 20 applications. CONCLUSIONS The monomer's variation in chemical composition, solvent and application technique of the bonding systems had an influence on contamination by the total number of bacteria and on the inhibitory effect on SM.