Inhibitory effect of resin composite containing S-PRG filler on Streptococcus mutans glucose metabolism

Objectives: Resin composites containing surface pre-reacted glass-ionomer (S-PRG) fillers have been reported to inhibit Streptococcus mutans growth on their surfaces, and their inhibitory effects were attributed to BO₃³⁻ and F⁻ ions. The aim of this study was to evaluate S. mutans acid production through glucose metabolism on resin composite containing S-PRG fillers and assess inhibitory effects of BO₃³⁻ and F⁻ on S. mutans metabolic activities. Methods: The pH change through S. mutans acid production on experimental resin composite was periodically measured after the addition of glucose. Inhibitory effects of BO₃³⁻ or F⁻ solutions on S. mutans metabolism were evaluated by XTT assays and measurement of the acid production rate. Results: The pH of experimental resin containing S-PRG fillers was significantly higher than that of control resin containing silica fillers (p < 0.05). OD₄₅₀ values by XTT assays and S. mutans acid production rates significantly decreased in the presence of BO₃³⁻ and F⁻ compared with the absence of these ions (p < 0.05). Conclusions: pH reduction by S. mutans acid production was inhibited on resin composite containing S-PRG fillers. Moreover, S. mutans glucose metabolism and acid production were inhibited in the presence of low concentrations of BO₃³⁻ or F⁻. Clinical significance: BO₃³⁻ or F⁻ released from resin composite containing S-PRG fillers exhibits inhibitory effects on S. mutans metabolism at concentrations lower than those which inhibit bacterial growth.