A soft, thin film of food debris, mucin, and dead epithelial cells deposited on the teeth, providing the medium for the growth of various bacteria. The main inorganic components are calcium and phosphorus, with small amounts of magnesium, potassium, and sodium; the organic matrix consists of polysaccharides, proteins, carbohydrates, lipids, and other components. Plaque plays an important etiologic role in the development of dental caries and periodontal and gingival diseases and provides the base for the development of materia alba; calcified plaque forms dental calculus. [ http://purl.obolibrary.org/obo/BTO_0000338 ]