Cytotoxicity of chlorhexidine-hydrogen peroxide combination in different concentrations on cultured human periodontal ligament fibroblasts

BACKGROUND: A strong antimicrobial synergism between chlorhexidine (CHX) and hydrogen peroxide (H(2)O(2)) has been reported, but there is not enough data on the cytotoxicity of this combination. The primary aim of this study was to evaluate the cytotoxicity of CHX-H(2)O(2) combination in different concentrations and secondary aim is to assess the influence of H(2)O(2) on cytotoxicity of CHX on cultured human periodontal ligament (PDL) fibroblasts. MATERIALS AND METHODS: The PDL cells were cultured from healthy human third molar teeth and were exposed to six prepared solutions (0.2% and 2% CHX separately and in combination with 1% and 3% H(2)O(2)). The MTT assay was applied to assess their effects on the viability of the PDL cells. Two-way analysis of variance approach and subgroup analysis was performed to evaluate the differences in mean cell viability values. A level of P < 0.05 was considered as statistically significant. RESULTS: All tested solutions were toxic to PDL cells. There was a significant interaction effect between CHX and H(2)O(2). The 2% CHX combined with 3% H(2)O(2) was the most and 0.2% CHX was the least cytotoxic solutions. The 2% CHX was significantly more toxic than 0.2% CHX and H(2)O(2) combinations. The cytotoxicity of 0.2% CHX and H(2)O(2) combinations did not significantly rise by increasing the concentration of H(2)O(2) from 1% to 3%. CONCLUSION: H(2)O(2) affected the cytotoxicity of CHX in a variable concentration-dependent manner. Based on the results of this study, it can be concluded that 2% CHX alone and in combination with either 1 or 3% H(2)O(2) are significantly more toxic than 0.2% CHX alone and in combination with 1 and 3% H(2)O(2). Therefore, to benefit from the synergistic antimicrobial effect between CHX and H(2)O(2), with a minimal cytotoxicity, it is recommended to use 0.2% concentration of CHX combined with 3% H(2)O(2).