The first is inflammatory product circulation (shown in Figure 2) where the biosynthesis of pro-inflammatory cytokines in the blood serum and gingival fluid (such as IL-1b, IL-6, PGE2, and TNF-a) can be up-regulated by cellular exposure to bacterial products (Gibbs et al., 1992), such as the lipopolysaccharides of the gram-negative anaerobic bacteria of periodontal disease (e.g., Tannerella forsythia, Porphyromonas gingivalis). Here, IL6 is linked to periodontal disorder.