Various in vivo and in vitro investigations have indicated that tobacco smoking as well as the use of smokeless tobacco products may be important risk factors for the development and severity of inflammatory periodontal disease. The purpose of this study was to determine the cytotoxicity of nicotine by means of human primary oral fibroblast cultures and a permanent cell line. The cytotoxicity of nicotine was evaluated by determination of cell growth, cell membrane integrity, protein content, and alterations of the cytoskeleton. Furthermore, recovery following nicotine exposure was assessed by vital staining (trypan blue). Dose-dependent toxic effects of nicotine were measured within a range of 0.48 mM to 62 mM. Growth of fibroblasts was decreased by nicotine concentrations higher than 7.8 mM. Additionally, the protein content was significantly decreased and cell membranes were damaged. Morphological alterations of microtubules and vimentin filaments were observed at concentrations higher than 3.9 mM. Nicotine-exposed cells revealed atypical shapes and vacuoles. The toxic effects of nicotine became irreversible in the range between 10.5 and 15.5 mM, whereas at lower concentrations cells recovered after the withdrawal of nicotine. Our results confirm clinical oberservations regarding the important role of nicotine as a risk factor in the etiology and progression of periodontal disease.

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