RESUMO
<p><b>OBJECTIVE</b>To study the role of fibrinogen molecule in the pathogenesis of periodontal diseases.</p><p><b>METHODS</b>An in vitro cell culture model was used. Methyl-(3)H Thymidine radiolabeled Porphyromonas gingivalis (Pg) ATCC 33277 were examined for their ability to adhere to and invade the confluent monolayers of human oral epithelial KB cells with or without exogenous human fibrinogens by scintillation spectrometry.</p><p><b>RESULTS</b>The addition of exogenous fibrinogens made more amount of and higher ratios of adhesive and invasive Pg, in contrast to the group without exogenous fibrinogen (P < 0.001). At different concentrations of exogenous fibrinogen, the amount and ratios of adhesive and invasive Pg varied significantly (P < or = 0.007). The higher concentrations of exogenous fibrinogen was added, the greater amount and ratios of adhesive and invasive Pg were found.</p><p><b>CONCLUSIONS</b>Fibrinogen promotes the adherence of Pg to human oral epithelial cells and may play an important role in the pathogenesis of periodontal diseases.</p>