Cytotoxic effect of chlorhexidine on immortalized odontoblast-like cells - MDPC-23

Objectives: The aim of the present study was to evaluate cytotoxic effects of different concentrations of chlorhexidine (CHX) applied to an immortalized odontoblast cell line MDPC-23. Methods: The cells plated (30,000 cells/cm²) in wells of 24 well-dishes were maintained in a humidified incubator, with 5% of CO₂ and 95% of air for 72 hours. Then, these cells were exposed for 120 minutes to the following experimental solutions: Group 1: CHX 0.12%; Group 2: CHX 0.2%; Group 3: CHX 1% and Group 4: calcium hydroxide solution (CH). In the negative and positive control groups the cells were exposed to phosphate buffer saline solution (Group 5: PBS) and hydrogen peroxide (Group 6: H₂O₂), respectively. Immediately after the experimental period, the cell metabolism was determined by the methyltetrazolium (MTT) assay. The numerical data obtained were submitted to the statistical analysis of Kruskal-Wallis complemented by Dunn method. Results: It was demonstrated that all CHX solutions depressed the cell metabolism. This decreasing cell metabolism caused by CHX solutions was dose-dependent. In Groups 1 and 2, the reduction of the cell metabolism was 24.85% and 29.93%, respectively. For Groups 3 and 6 (positive control), this reduction was 70.48% and 86.61%, respectively. The difference between these two groups was not statistically significant. In Group 4 (CH) and 5 (positive control), it was not determined changes in the metabolic activity of the cells in contact with the experimental and control solutions. Conclusions: According to the experimental conditions, it was possible to conclude that CHX solutions with concentrations about 0.12% and 0.2% caused lower cytotoxic effects on the odontoblast-like cells MDPC-23 when compared to 1% CHX. Hydrogen peroxide and 1% CHX exhibited the highest cytopathic effects to the cultured cells.