In
dentistry,
calculus or
tartar is a form of hardened
dental plaque. It is caused by precipitation of minerals from
saliva and gingival crevicular fluid (GCF) in plaque on the
teeth. This process of precipitation kills the bacterial cells within dental plaque, but the rough and hardened surface that is formed provides an ideal surface for further plaque formation. This leads to calculus buildup, which compromises the health of the
gingiva (gums). 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").