Abstract
Dental plaque is a complex microbial community that develops on the tooth surface, embedded in a matrix of polymers of bacterial origin. Dental plaque is considered as one of the biofilms of the organism and dental caries and periodontitis are recognized as biofilm associated infections. Dental plaque formation is initiated by formation of conditioning film, termed acquired pellicle, on the tooth enamel. Microorganisms are transported to the tooth surface by flow of saliva. As a particle approaches on surface, it experiences a weak van der Waals attraction. These weak physicochemical interactions become irreversible due to adhesins on the microbial cell surface becoming involved in specific interactions with complementary receptors in acquired pellicle. Some organisms that were unable to colonize the pellicle–coated tooth surfaces are able to attach to already–adherent pioneer species by adhesion–receptor interactions. The close proximity of cells with each other in dental plaque provides the conditions for cell–cell interactions. As conventional interactions, cell density–dependent gene expressions called quorum sensing (QS) are reported. In Streptococcus mutans, human cariogenic pathogen, QS regulate the expression of glucosyltransferase (GTF) genes. The synthesized glucose polymer by GTFs is extracellular matrix of biofilm and one of the crucial virulence factors of S. mutans.
