Biofilm

Bacteria collect on specific sites of the teeth and along the edge of the gums in a cream-colored mass called plaque (Figure 5). 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.^11-13 The extracellular polysaccharides also form a hydrophobic layer that helps bacteria in biofilm to evade antibodies and protect the microorganisms from antibiotics, fluorides, and antimicrobials.

Figure 5. Dental Plaque Deposits.

Figure 5. Dental Plaque Deposits.

From: V. Kim Kutsch, DDS. Originally published in Inside Dentistry, 2009;5(5):60-65.