New insights into mechanisms of bacterial pathogenesis in periodontitis.

This review focuses on two topics that in the past decade have significantly enhanced our understanding of the mechanisms by which bacteria produce disease in humans: population structures of bacterial pathogens and tactics used by these bacteria to gain entry to mammalian cells. Studies in these areas have identified a number of virulence factors of some medically important pathogens. Very recent applications of this knowledge in efforts to understand mechanisms by which the most extensively studied "putative" periodontal pathogens, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans, may contribute to the pathogenesis of periodontitis are presented. Knowledge of the population structures of these periodontopathic bacterial species and the mechanisms used by these bacteria to subvert host cell communication systems and functions will shape future approaches to diagnosis, prevention, and treatment of periodontal diseases.