Exopolysaccharide Productivity and Biofilm Phenotype on Oral Commensal Bacteria as Pathogenesis of Chronic Periodontitis

Exopolysaccharide (EPS) productivities in many bacteria have been associated with pathogenicity in mammalian hosts as providing extracellular matrices to form biofilm (Costerton et al., 1995). Bacteria assuming biofilm-forming capacity have enormous advantages in establishing persistent infections (Costerton et al., 1999). Chronic periodontitis is caused by dental plaque known as a complex biofilm which consists of several hundred different species of bacteria (Chen, 2001; Socransky and Haffajee, 2002; Lovegrove, 2004). While sucrose-derived homopolysaccharides are well known substrates which mediate adhesion of bacteria to the tooth surface and co-aggregation interactions between species of oral bacteria in the dental plaque (Russell, 2009), recent studies suggest that each bacterium produces distinctive EPS components in a sucrose-independent manner and can form so called single species biofilm (Branda et al., 2005). In the oral cavity, several species of oral bacteria are known to produce their own EPS with this manner (Okuda et al., 1987; Dyer and Bolton, 1985; Kaplan et al., 2004; Yamane et al., 2005; Yamanaka et al., 2009; Yamanaka et al., 2010). In this chapter, we will describe a possibility that a single species biofilm in the oral cavity can cause persistent chronic periodontitis along with the importance of dental plaque formation and maturation with sucrose-derived polysaccharides.