calculus /kal″kyələs/ pl. calculi [L, little stone] , 1. an abnormal stone formed in body tissues by an accumulation of mineral salts. Calculi are usually found in biliary and urinary tracts. Also called stone. Kinds include biliary calculus, renal calculus. 2. (in dentistry) a deposit of mineralized bacterial plaque biofilm, calcium phosphate, calcium carbonate, and organic matter that accumulates on the teeth or a dental prosthesis. Calculus that forms coronal to the gingival crest, called supragingival calculus, is chalky and cream-colored but may be stained by drinks such as tea or coffee, tobacco, and food. Calculus that forms in the gingival pocket, or the periodontal pocket, called serumal calculus, subgingival calculus, or veneer, is usually denser and darker than supragingival calculus; slight deposits may be invisible until dried with air, lending a chalky appearance. It harbors bacteria, Also called tartar. See also serumal calculus, subgingival calculus, veneer, def. 2.
