Dental plaque is a type of biofilm that forms on and around the teeth and gums (magnified image has been colorized for clarity). If not removed regularly, plaque can lead to dental caries (cavities), gingivitis and periodontal disease.
The microorganisms that form the plaque biofilm are almost entirely bacteria (mainly Streptococcus mutans and various anaerobes), with the composition varying by location in the mouth.
These microorganisms are all naturally present in the oral cavity and are normally harmless. However, in order to maintain a healthy mouth and body, it is essential that the bacterial plaque is kept at an minimum volume through daily toothbrushing and flossing as well as regularly scheduled professional dental cleanings. Infection occurs when the bacteria is allowed to grow and mutate into a harmful form that overpowers the body’s natural resistance.
When this layer of bacteria is exposed to the naturally occuring minerals in saliva, it hardens to form calculus (tartar). Once calculus has formed it acts as an irritant to the tissues and an attractant for additional plaque formation. Calculus must be removed by a licensed dental hygienist or a periodontist.
Acids released from dental plaque lead to demineralization of the tooth surface resulting in dental caries (cavities). The composition and character of healthy saliva acts to protect the teeth through remineralization and promotes the health of the oral mucosal and gingival tissues. However, a thickened plaque biofilm layer does not allow for salivary access to the tooth surface where it can act to neutralize the acid produced by bacteria and remineralize the tooth surface.