Cytotoxic effects of different concentrations of a carbamide peroxide bleaching gel on odontoblast-like cells MDPC-23

This study evaluated the cytotoxic effects of a carbamide peroxide (CP) bleaching gel at different concentrations on odontoblast‐like cells. Immortalized cells of the MDPC‐23 cell line (30,000 cells/cm2) were incubated for 48 h. The bleaching gel was diluted in DMEM culture medium originating extracts with different CP concentrations. The amount (μg/mL) of hydrogen peroxide (H2O2) released from each extract was measured by the leukocrystal violet/horseradish peroxidase enzyme assay. Five groups (n = 10) were formed according to the CP concentration in the extracts: G1‐DMEM (control); G2‐0.0001% CP (0.025 μg/mL H2O2); G3‐0.001% CP (0.43 μg/mL H2O2); G4‐0.01% CP (2.21 μg/mL H2O2); and G5‐0.1% CP (29.74 μg/mL H2O2). MDPC‐23 cells were exposed to the bleaching gel extracts for 60 min and cell metabolism was evaluated by the MTT assay. Data were analyzed statistically by one‐way ANOVA and Tukey's test (α = 0.05). Cell morphology was examined by scanning electron microscopy. The percentages of viable cells were as follows: G1, 100%; G2, 89.41%; G3, 82.4%; G4, 61.5%; and G5, 23.0%. G2 and G3 did not differ significantly (p > 0.05) from G1. The most severe cytotoxic effects were observed in G3 and G4. In conclusion, even at low concentrations, the CP gel extracts presented cytotoxic effects. This cytotoxicity was dose‐dependent, and the 0.1% CP concentration caused the most intense cytopathic effects to the MDPC‐23 cells. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2009