The effect of a commercially available chlorhexidine mouthwash product on human osteoblast cells

Chlorhexidine mouthwash (CMW) is used for decontamination of tooth, implant or prosthetic surfaces to treat or prevent local infection. A cell culture model was used to investigate cytotoxicity of CMW employing an MTT assay to record cell activity. Human osteoblast-like cells (HOS TE 85) were seeded. Dilutions of CMW (1:1 to 1:128) were made up with culture medium. Positive and negative controls were prepared. Cells were incubated, exposed to CMW, for 5 min to 4 h. Diluted tetrazolium salt solution was added. Plates were incubated for a further 4 h. Medium was removed, dimethylsulphoxide was added, and absorbance at 570nm read. Undiluted CMW caused total cytotoxicity, similar to positive control. Progessive dilution of CMW was associated with elevated cell survival. Cytotoxicity increased with longer time exposures. It was concluded that CMW can be cytotoxic in high concentrations and when applied for long time periods. Work is needed to determine effects on other cell types and clinical significance of these findings.