Periodontitis is a polymicrobial infectious disease of multifactorial origin. Plaque biofilm and associated host responses are involved in the pathogenesis of periodontitis. Organisms strongly implicated as etiologic agents include Gramnegative, anaerobic bacteria within the biofilm . The microbial challenge consisting of antigens,lipopolysaccharide (LPS), and other virulence factors stimulates host responses which result in disease. Protective aspects of the host response include recruitment of neutrophils, production of protective antibodies, and possibly the release of anti-inflammatory cytokines including transforming growth factor-β (TGF-β), interleukin-4,10,12 Perpetuation of the host response due to a persistent bacterial challenge disrupts homeostatic mechanisms and results in release of mediators including proinflammatory cytokines, proteases,and prostanoids which can promote extracellular matrix destruction in the gingiva and stimulate bone resorption. The determination that periodontal tissue destruction is primarily due to the host response has created areas of research directed at altering an individual's reaction to the bacterial challenge. Hence Host modulation....