In dentistry, calculus or tartar refers to calcified deposits on the teeth, formed by the continuous presence of dental plaque. Its rough surface provides an ideal medium for further plaque formation, threatening the health of the gingiva. Calculus absorbs unaesthetic stains far more easily than natural teeth.
Calculus accumulations occur in the absence of adequate oral care. Once formed, it is generally too firmly adherent to teeth to be removed with anything available to an individual at home; patients with calculus must therefore visit their dental professionals so that the calculus can be removed with ultrasonic tools and specialized sharp instruments.
Calculus can form both along the gumline, where it is referred to as supragingival ("above the gum"), and within the narrow sulcus that exists between the teeth and the gingiva, where it is referred to as subgingival ("below the gum"). Calculus formation can result in a number of clinical manifestations, including bad breath, receding gums and chronically inflamed gingiva.
When plaque is supragingival, the bacterial content consists mostly of aerobic bacteria, or those bacteria which utilize and can survive in an environment containing oxygen. Subgingival plaque, however, is composed mainly of anaerobic bacteria, or those bacteria which cannot exist in an environment containing oxygen. Anaerobic bacteria are especially dangerous to the gingiva and the gingival fibers that attach the teeth to the gums, leading to periodontitis. Almost all individuals with periodontitis exhibit considerable subgingival calculus deposits. These anaerobic bacteria have been linked to cardiovascular disease and pre-term low birth weight babies, but there is no conclusive evidence yet that periodontitis is a significant risk factor for either of these two conditions.