calculus

Definition calculus

calculus: calculus n. (pl. calculi) 1.a stone: a hard pebble-like mass formed within the body, particularly in the gall bladder (see gallstone) or anywhere in the urinary tract (see cystolithiasis,nephrolithiasis). Calculi in the urinary tract are commonly composed of calcium oxalate and are usually visible on X-ray examination. Most of these stones cause pain, whether sited in the kidney, ureter, or bladder; stones passing doen a duct (such as the ureter) cause severe colicky pain. Such stones are usually removed surgically to prevent or cure urinary obstruction and infection. 2. a calcified deposit that forms on the surfaces of teeth. Supragingival calculus forms above the *gingivae (gums), principally in relation to the opening of the salivary gland ducts. Subgingival calculus forms beneath the crest of the gingivae. Calculus hinders the cleaning of teeth.