Cytotoxic effect of a 35% hydrogen peroxide bleaching gel on odontoblast-like MDPC-23 cells.

Objective: This study evaluated transenamel and transdentinal cytotoxic effects of a bleaching gel on the MDPC-23 cell line.

Study Design: Discs obtained from bovine incisors were placed in a metallic device to simulate an in vivo pulp chamber. Groups were formed according to the enamel surface treatment: G1: 35% H(2)O(2) bleaching gel; G2: 35% H(2)O(2) bleaching gel + halogen light; G3: halogen light; and G4: control. Cell metabolism was evaluated by the methyltetrazolium assay and cell morphology by scanning electron microscopy.

Results: Cell metabolism decreased by 31.7%, 41.6%, and 11.5% in G1, G2, and G3, respectively. Cytotoxic effects observed in G2 were significantly more severe compared with G3 and G4. In G1 and G2, a smaller number of viable cells with major morphologic alterations remained adhered to dentin.

Conclusion: The bleaching gel associated with light presented transenamel and transdentinal cytotoxic effects characterised by direct damage to odontoblasts and decrease of their metabolic activity.