Assessment of the cytotoxicity of chlorhexidine by employing an in vitro mammalian test system

Background/purpose: Chlorhexidine (CHX), a chlorophenyl biguanide with broad antibacterial action, has been widely used in dentistry. The initial uses of CHX in dentistry were to wash operation site and to disinfect root canals. Recently, the addition of CHX into many dental materials has improved the overall therapeutic efficacy. The aim of this study was to evaluate the potential toxicological implications of CHX employing an in vitro mammalian test system. Materials and methods: Cytotoxicity, mode of cell death, and generation of superoxide anion were performed to elucidate the toxic effects of CHX on Chinese hamster ovary cells. Cytotoxicity was judged using tetrazolium bromide reduction assay. The mode of cell death was determined by flow cytometry. Superoxide anion generation was determined by the superoxide dismutase-inhibitable reduction of ferricytochrome c. Results: CHX demonstrated a cytotoxic effect on Chinese hamster ovary cells in a dose-dependent and time-dependent manner (P < 0.05). The mode of cell death changed from apoptosis to necrosis as the concentrations of CHX elevated. CHX demonstrated a significant superoxide anion generation in a dose-dependent manner (P < 0.05). The addition of superoxide dismutase decreased the cytotoxicity induced by CHX (P < 0.05). Conclusion: CHX was demonstrated to exhibit cytotoxicity that could disrupt the stable cellular redox balance, resulting in increasing levels of free radical generation and subsequent cell death. CHX has significant potential for cytotoxicity. Copyright (C) 2013, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.