Cytotoxic Effects of Hydrogen Peroxide on Human Gingival Fibroblasts In Vitro

In-office bleaching is a popular treatment in modern esthetic dentistry. However, bleaching agents sometimes accidentally adhere to the gingiva and peripheral tissues, even when applied by well-trained dentists. This can lead to transient pain and whitish changes in the gingiva. Although these symptoms disappear within several hours, the effects of bleaching agents on gingiva have not been well described in the literature. The present study aimed to elucidate the cytotoxic effects of a bleaching agent on cultured human gingival fibroblasts (HGFs). We performed a comprehensive analysis of the toxic effects of in-office bleaching agents on gingiva using cultured HGFs and DNA microarray. Survival rates of HGFs decreased with increases in the concentration of hydrogen peroxide, which became significant at concentrations of 1.5 × 10(-3)% or higher at every time point. Concentrations lower than 1.5 × 10(-3)% did not affect survival rates of HGFs. Cytotoxicity of hydrogen peroxide was significantly weakened by the addition of vitamin E. Stimulation by in-office bleaching agents triggered the proinflammatory cytokine tumor necrosis factor (TNF)-α cascade in gingival fibroblasts. As the TNF-α cascade can be inhibited by vitamin E additives, treatment with vitamin E may protect gingival fibroblasts against the toxic effects of an in-office bleaching agent. The present results suggest that local administration of vitamin E to gingiva before in-office bleaching may be useful for preventing gingival irritation due to accidental adhesion of a bleaching agent.