Calculus

Calculus consists of mineralized bacterial plaque that forms on the surfaces of natural teeth and dental prostheses.

Types of Calculus

Supragingival calculus

• Supragingival calculus is located coronal to the gingival margin and therefore is visible in the oral cavity.
• It is usually white or whitish yellow in color; hard, with a claylike consistency; and easily detached from the tooth surface. After removal, it may rapidly recur, especially in the lingual area of the mandibular incisors.
• The color is influenced by contact with such substances as tobacco and food pigments.
• It may localize on a single tooth or group of teeth, or it may be generalized throughout the mouth. The two most common locations for the development of supragingival calculus are the buccal surfaces of the maxillary molars and the lingual surfaces of the mandibular anterior teeth Saliva from the parotid gland flows over the facial surfaces of the upper molars via the parotid duct, whereas the submandibular duct and the lingual duct empty onto the lingual surfaces of the lower incisors from the submaxillary and sublingual glands, respectively.
• In extreme cases, calculus may form a bridgelike structure over the interdental papilla of adjacent teeth or cover the occlusal surface of teeth that are lacking functional antagonists.

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  MandibularAnteriorCalculus

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  Calculus deposit on x-ray image

Subgingival calculus

• Subgingival calculus is located below the crest of the marginal gingiva and therefore is not visible on routine clinical examination. The location and extent of subgingival calculus may be evaluated by careful tactile perception with a delicate dental instrument such as an explorer. Subgingival calculus is typically hard and dense; it frequently appears to be dark brown or greenish black in color, and it is firmly attached to the tooth surface.

Composition

Inorganic Content

Supragingival calculus consists of inorganic(70% to 90%) and organic components. The major inorganic proportions of calculus have been reported as approximately 76% calcium phosphate, (Ca3[PO4]2); 3% calcium carbonate (CaCO3); and traces of magnesium phosphate (Mg3[PO4]2) and other metals. The percentage of inorganic constituents in calculus is similar to that of other calcified tissues of the body. The principal inorganic components have been reported as approximately 39% calcium, 19% phosphorus, 2% carbon dioxide, and 1% magnesium as well as trace amounts of sodium, zinc, strontium, bromine, copper, manganese, tungsten, gold, aluminum, silicon, iron, and fluorine. At least two thirds of the inorganic component is crystalline in structure. The four main crystal forms and their approximate percentages are as follows: hydroxyapatite, 58%; magnesium whitlockite, 21%; octacalcium phosphate, 12%; and brushite, 9%. Two or more crystal forms are typically found in a sample of calculus. Hydroxyapatite and octacalcium phosphate are detected most frequently (i.e., in 97% to 100% of all supragingival calculus) and constitute the bulk of the specimen. Brushite is more common in the mandibular anterior region, and magnesium whitlockite is found in the posterior areas. The incidence of the four crystal forms varies with the age of the deposit.

Organic Content

The organic component of calculus consists of a mixture of protein–polysaccharide complexes, desquamated epithelial cells, leukocytes, and various types of microorganisms. Between 1.9% and 9.1% of the organic component is carbohydrate, which consists of galactose, glucose, rhamnose, mannose, glucuronic acid, galactosamine, and sometimes arabinose, galacturonic acid, and glucosamine. All of these organic components are present in salivary glycoprotein, with the exception of arabinose and rhamnose. Salivary proteins account for 5.9% to 8.2% of the organic component of calculus and include most amino acids. Lipids account for 0.2% of the organic content in the form of neutral fats, free fatty acids, cholesterol, cholesterol esters, and phospholipids. The composition of subgingival calculus is similar to that of supragingival calculus, with some differences. It has the same hydroxyapatite content, more magnesium whitlockite, and less brushite and octacalcium phosphate. The ratio of calcium to phosphate is higher subgingivally, and the sodium content increases with the depth of periodontal pockets.94 These altered compositions may be attributed to the origin of subgingival calculus being plasma, whereas supragingival calculus is partially composed of saliva constituents. Salivary proteins present in supragingival calculus are not found subgingivally.11 Dental calculus, salivary duct calculus, and calcified dental tissues are similar in inorganic composition.

Calculus Resources
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