Capacity of a hydroxyapatite–lysozyme combination against Streptococcus mutans for the treatment of dentinal caries

BACKGROUND: One current strategy for the treatment of carious lesions is the use of biomaterials with antimicrobial activity. AIMS: The aim of this study was to evaluate a combination of hydroxyapatite and lysozyme for the treatment of dentinal caries by measuring Streptococcus mutans counts before carious tissue sealing, and 24 h, 1 month, and 6 months after treatment. MATERIALS AND METHODS: Forty permanent third molars were selected, and flat dentin surfaces were prepared. The teeth were exposed to a cariogenic challenge with S. mutans. After challenge, the dentinal caries were collected from five specimens. The remaining specimens were treated with a mixture of hydroxyapatite and lysozyme in sodium laureth sulfate and sealed with composite resin. S. mutans counts were obtained 24 h, 1 month, and 6 months after sealing. STATISTICAL ANALYSIS: The results were evaluated by descriptive statistics and Wilcoxon signed-rank test. RESULTS: a significant reduction in S. mutans (CFU/mL) was observed in dentinal lesions 1 month after treatment with hydroxyapatite/lysozyme in sodium laureth sulfate (P = 0.0254). Comparison of S. mutans counts obtained 24 h, 1 month, and 6 months after treatment revealed reductions only at the 1-month time point (P = 0.0318). CONCLUSIONS: the combination of hydroxyapatite and lysozyme may be an alternative for reducing the S. mutans burden in dentinal caries.