Efficacy of vitamins E and C for reversing the cytotoxic effects of nicotine and cotinine

Nicotine has adverse cellular and molecular effects on oral mucosa, bone, and teeth. Vitamin E (α‐tocopherol) and vitamin C (ascorbic acid) are biological antioxidants with positive effects on wound healing and bone formation. This in vitro study sought to assess the cytotoxic effects of different concentrations of nicotine and cotinine (a metabolite of nicotine) on MG‐63 osteoblast‐like cells and human gingival fibroblasts (HGFs) in the presence and absence of antioxidant vitamins E and C (separately and combined). Cell viability and proliferation were assessed using the methyl thiazol tetrazolium (MTT) assay. Cell migration was assessed using the scratch test, and expression of apoptosis‐related genes was quantitatively analyzed using real‐time PCR. Dose‐dependent negative effects of nicotine on the morphology, viability, proliferation, and migration of MG‐63 and HGF cells were statistically significantly greater than those of cotinine. Vitamin E (separately and combined with vitamin C) was statistically significantly more effective than vitamin C (at the concentration used in this study) at improving cell viability, proliferation, and migration, and at reducing apoptosis of cells exposed to nicotine or cotinine. Based on the positive results of this study, vitamin C and especially vitamin E (systemically and/or locally) may be useful in the repair and regeneration of oral hard and soft tissues in smokers.