Dental Calculus

Dental Calculus Dental Calculus The primary cause of gingival inflammation is bacterial plaque, other predisposing factors including calculus, malocclusion, faulty restoration, complications associated with orthodontic therapy, self-inflicted injuries, use of tobacco, and radiation therapy. Calculus consists of mineralized bacterial plaque that forms on the surface of natural teeth and dental prosthesis and is classified as supragingival or subgingival according to its relation to the gingival margin. ➢ Classification of dental calculus : ❖ According to location : o Supragingival calculus o Subgingival calculus ❖ According to source of mineralization : (Jenkins, Stewart 1966) • Salivary calculus • Serumal calculus ❖ According to surface : (Melz 1950) o Exogenous o Endogenous ❖ According to initiation and rate of accumulation,: Calculus formers are classified as: • Non-calculus formers • Slight calculus formers • Moderate calculus formers • Heavy calculus formers. ➢ Supra and sub-gingival calculus (distribution and appearance) ❖ Supragingival calculus: is located coronal to the gingival margin and therefore visible in the oral cavity, it’s usually white to yellowish in color, hard with claylike consistency and easily detected from the tooth surface, after removal, it may rapidly recur, especially in the lingual area of the mandibular incisors, it’s 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 supragingival calculus to develop are the buccal surface of maxillary molars and the lingual surfaces of mandibular anterior teeth, saliva from the parotid gland flows over the facial surfaces of the upper molars via the parotid duct (Stensen's duct ), while the submandibular and the sublingual glands empty onto lingual surfaces of lower incisors via the submandibular (Warhtin’s duct) and sublingual ducts (Bartholins’duct) respectively. ❖ Subgingival calculus: is located below the crest of the marginal gingiva and therefore not visible on routine clinical examination, the location and extent of the subgingival calculus maybe evaluated by careful tactile perception with a delicate dental instruments such as a dental explorer, subgingival calculus is typically hard and dense, frequently appears dark brown or greenish black in color and firmly attached to the tooth surface. When the gingival tissue recede, subgingival calculus becomes exposed and its therefore classified as supragingival. A reduction in the gingival inflammation and probing depths with a gain in clinical attachment can be observed after the removal of subgingival plaque and calculus. Both supra and sub gingival calculus may be seen by radiograph. ➢ 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); 3% calcium carbonate CaCO3; traces of magnesium phosphate Mg3(PO4) and other metals (Na, Ba, Zn, Str, Br, Cu, Ag, Al, Fe, Fl). The percentage of inorganic constituents in calculus is similar to that in other calcified tissue of the body, the principle inorganic components have been reported as approximately 39% calcium, 19% phosphorus, 2% carbon dioxide and 1% magnesium and trace amounts of sodium, zinc, strontium, bromine, copper, manganese, tungsten, aluminum, silicon. At least two thirds of the inorganic component is crystalline in structure, the four main crystal forms and their approximate percentage are as follows: hydroxyapatite 58%, magnesium white-lockite 21%, octacalcium phosphate 12% and brushite 9%. Generally two or more crystal forms are typically found in the sample of calculus hydroxyapatite and octacalcium phosphate are detected most frequently (i.e. in 97% to 100%of the supragingival calculus) and constitute the bulk of the specimen. Brushite is more common in the mandibular anterior region and magnesium whitelockite is in the posterior areas, the incidence of the four crystals varies with the age of the deposit. The composition of subgingival calculus is similar to that of supragingival calculus with some differences, it has the same hydroxyapatite content, more magnesium white-lockit, and less brushite and octacalcium phosphate than supragingival calculus. • Organic content: the organic component of calculus consists of a mixture of protein-polysaccharide complexes, desquamated epithelial cells. Leukocytes and various types of microorganisms. Salivary proteins present in supragingival calculus are not found subgingivally. The ratio of calcium to phosphate is higher subgingivally and the sodium content increases with the depth of periodontal pockets.