Bacteria collect on the teeth and along the edge of the gums in a cream-colored mass called plaque (Figure 2). The bacterial deposits that form plaque on teeth differ considerably from that on soft tissues because teeth are a non-shedding surface, allowing more time for the development of a “structure” consisting of multiple layers of bacteria. This plaque “structure” also serves as a biofilm, typically defined as an aggregate of microorganisms in which cells adhere to each other and/or to a solid substrate exposed to an aqueous surface. The bulk of the volume (~90%) of dental plaque biofilm is comprised of a gel-like matrix of extracellular polysaccharides produced by oral bacteria. These polysaccharides are what holds the biofilm together and triggers changes that make it increasingly difficult to remove over time: When a cell becomes a component of biofilm, one of the many changes it experiences is a shift in gene expression that makes it up to 1,000 times more resistant to antibodies, antibiotics, and antimicrobial compounds than its planktonic (single cell) counterparts.9-11
Figure 2. Dental Plaque Deposits.