Evaluation of biofilm formation on composites containing bioactive glass-triterpenoids

Objectives: To assess the inhibitory effect  on biofilms of Streptococcus mutans formed on resin composites containing bioactive glass and/or triterpenoids.

Materials and Methods: Composite (71% Sr glass filler, 29% 50:50 bis-GMA:TEGDMA ) containing 10 wt% bioactive glass (BAG)(62 mol% SiO2, 31 mol% CaO, 4 mol% P₂O₅, and 3 mol% F), BAG coated with ursolic acid (total 0.5 wt% of composite, U6753, Sigma Aldrich, St. Louis, MO, U.S.A., BAG+UA) or oleanolic acid (total 0.5 wt% of composite, O5504, Sigma Aldrich, BAG+OA) were developed. Conventional composite (10%wt OX50 silica nanofiller instead of BAG) and resin monomer matrix were used as controls. For the biofilm assay, S. mutans UA159 was incubated for 24 hours with each composite resin disk specimen in a biofilm medium with either 20mM glucose or 20mM sucrose in the presence or absence of a salivary coating. The adherent bacteria were quantified after sonication of the specimen by counting the colony forming units of viable bacteria. Two-way ANOVA, with Bonferroni correction, was used for analyses (a=0.05).

Results: All composites containing BAG (BAG, BAG+UA, BAG+OA) significantly reduced the amount of biofilm formation of S. mutans regardless of the carbohydrate source and the salivary condition (Figures, p<0.05). There were no significant differences among BAG, BAG+UA, and BAG+OA groups (p>0.05).

Conclusions: Experimental composites containing BAG showed a significant reduction of the biofilm formation by S. mutans, with or without any salivary pre-treatment, and independent of carbohydrate source for less than 24 hours. Treatment with ursolic acid or oleanolic acid did not show any additional effects on decreasing biofilm formation. The results suggest that the incorporation of BAG into resin composites could be a useful approach to develop successful antibacterial composite resins.