Effects of nicotine on periodontal ligament fibroblasts in vitro

Cigarette smoking is associated with increased incidence of periodontal dis ease and poor response to therapy. In the present study, we examined the ef fects of nicotine on several functions of periodontal ligament fibroblasts (PDLF): proliferation, attachment, alkaline phosphatase production and chem otaxis. Nicotine concentrations varying from 5 ng/ml to 250 mu g/ml were te sted. Proliferation of cells was studied by the incorporation of H-3-thymid ine, and a dose-dependent inhibition was observed with concentrations great er than or equal to 100 ng/ml. Similar results were observed when studying the attachment of the cells on plastic surfaces, using a colorimetric metho d. The inhibition of attachment was even more evident after 6 h incubation of the cells with nicotine. The activity of alkaline phosphatase, as determ ined with the substrate p-nitrophenyl phosphate, in both conditioned medium (CM) and cellular extract (CE), was also significantly decreased in a conc entration-related fashion. Finally, the chemotaxis of PDLF as examined by a modification of the Boyden's blind-well chamber technique, was inhibited i n a dose-dependent manner. The degree of inhibition varied from 15% with th e lowest concentration of nicotine (50 ng/ml), to almost 90% with the highe st (5 mu g/ml). The results show that nicotine can have direct adverse effe cts on various functions of the periodontal cells.