Extracellular Polysaccharides Matrix — An Often Forgotten Virulence Factor in Oral Biofilm Research

Oral diseases related to dental biofilms continue to afflict the majority of the world's population.Among them, dental caries continues to be the single most prevalent and costly oral infectious disease (Marsh, 2003;Dye et al., 2007).Dental caries results from the interaction of specific bacteria with constituents of the diet within a dental biofilm known as plaque (Bowen, 2002).Sucrose is considered to be the "arch criminal" from the dietary aspect because it serves as a substrate for synthesis of extracellular (EPS) and intracellular (IPS) polysaccharides in dental biofilm and is also fermentable (Bowen, 2002).However, it is important to emphasize that additional sugars and starch can certainly contribute to the pathogenesis (Bowen et al., 1980;Firestone et al., 1982;Thurnheer et al., 2008).Streptococcus mutans (S. mutans), a member of the oral microbial community, is generally regarded as the primary microbial culprit although additional microorganisms may be involved (Hamada and Slade, 1980;Loesche, 1986;Beighton, 2005).This bacterium (i) effectively utilizes dietary sucrose (and possibly starch) to synthesize large amounts of EPS through glucosyltransferases (Gtfs) and a fructosyltransferase (Ftfs), (ii) adheres tenaciously to glucan-coated surfaces, and (iii) is also acidogenic and acid-tolerant, which are critical virulence properties involved in the pathogenesis of dental caries.