dental calculus

The Role of Dental Calculus and Other Local Predisposing Factors Dr. Amira Izzeldin Altay BDS, MSc of Anatomy, Md of Periodontology, PPD of Implantology Assistant professor of periodontology Calculus Consists of mineralized bacterial plaque that forms on the surfaces of natural t...

The Role of Dental Calculus and Other Local Predisposing Factors Dr. Amira Izzeldin Altay BDS, MSc of Anatomy, Md of Periodontology, PPD of Implantology Assistant professor of periodontology Calculus Consists of mineralized bacterial plaque that forms on the surfaces of natural teeth and dental prostheses. Supragingival calculus located coronal to the gingival margin Visible in the oral cavity. 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 substances such as tobacco and food pigments. It may be localized 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 1. buccal surfaces of the maxillary molars 2. Lingual surfaces of the mandibular anterior teeth.  Subgingival calculus Located below the crest of the marginal gingiva and therefore is not visible on routine clinical examination. The location and the extent of subgingival calculus may be evaluated by dental instrument such as an explorer. Subgingival calculus is typically hard and dense. Appears to be dark brown or greenish-black in color.  Supragingival calculus and subgingival calculus generally occur together, but one may be present without the other. Microscopically deposits of subgingival calculus extend nearly to the base of periodontal pockets in individuals with chronic periodontitis but do not reach the junctional epithelium.  Both supragingival calculus and subgingival calculus may be seen on radiographs. Highly calcified interproximal calculus deposits are readily detectable as radiopaque projections that protrude into the interdental spaces Composition 1.Inorganic Content Dental calculus is primarily composed of inorganic components (70% to 90%). The major inorganic proportions of calculus are approximately 76% calcium phosphate (Ca3[PO4]2), 3% calcium carbonate (CaCO3), 4% magnesium phosphate (Mg3[PO4]2), 2% carbon dioxide, and Traces of other elements such as sodium, zinc, 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 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. Composition 2. Organic Content : The organic component of calculus consists 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, etc  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 but more magnesium whitlockite and less brushite and octacalcium phosphate  The ratio of calcium to phosphate is higher in subgingival calculus, and the sodium content increases with the depth of periodontal pockets. Dental calculus, salivary duct calculus, and calcified dental tissues are similar in inorganic composition. Attachment to the Tooth Surface Differences in the manner in which calculus is attached to the tooth surface affect the relative ease or difficulty encountered during its removal. Four modes of attachment 1. Attachment by means of an organic pellicle on cementum and or enamel 2. Mechanical locking into surface irregularities, such as caries lesions or resorption lacunae. 3. Close adaptation of the undersurface of calculus to depressions or gently sloping mounds of the unaltered cementum surface 4. Penetration of bacterial calculus into cementum. Formation Calculus is mineralized dental plaque. The soft plaque is hardened by the precipitation of mineral salts, which usually starts between the 1st and 14th day of plaque formation. Calcification occur within 4 to 8 hours. Calcifying plaques may become 50% mineralized in 2 days and 60% to 90% mineralized in 12 days. All plaque does not necessarily undergo calcification.  Early plaque contains a small amount of inorganic material, which increases as the plaque develops into calculus. Plaque that does not develop into calculus reaches a plateau of maximal mineral content within 2 days.  Saliva is the primary source of mineralization for supragingival calculus, whereas the gingival crevicular fluid furnishes the minerals for subgingival calculus. The calcium concentration or content in plaque is 2 to 20 times higher than in saliva. Early plaque of heavy calculus formers contains more vulnerability of bulky calculus to mechanical wear from food and from the cheeks, lips, and tongue movement.  Role of Microorganisms in the Mineralization of Calculus : Mineralization of plaque generally starts extracellularly around both gram-positive and gram-negative organisms, but it may also start intracellularly. Etiologic Significance : Distinguishing between the effects of calculus and plaque on the gingiva is difficult, because calculus is always covered with a nonmineralized layer of plaque. A positive correlation between the presence of calculus and the prevalence of gingivitis exists, but this correlation is not as great as that between plaque and gingivitis. Calculus does not contribute directly to gingival inflammation, but it provides a fixed nidus for the continued accumulation of bacterial plaque and its retention in close proximity to the gingiva.  Periodontal pathogens such as Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Treponema denticola have been found within the structural channels and lacunae of supragingival and subgingival calculus. Bacterial plaque that coats the teeth is the main etiologic factor in the development of periodontal disease, the removal of subgingival plaque and calculus constitutes the cornerstone of periodontal therapy. Calculus plays an important role in maintaining periodontal disease by keeping plaque in close contact with the gingival tissue and by creating areas where plaque removal is impossible.  Materia Alba, Food Debris, and Dental Stains Materia alba is an accumulation of microorganisms, desquamated epithelial cells, leukocytes, and a mixture of salivary proteins and lipids, with few or no food particles; it lacks the regular internal pattern observed in plaque. It is a yellow or grayish-white, soft, sticky deposit, and it is somewhat less adherent than dental plaque. The irritating effect of materia alba on the gingiva is caused by bacteria and their products.  Pigmented deposits on the tooth surface are called dental stains. Stains are primarily an aesthetic problem and do not cause inflammation of the gingiva. Iatrogenic Factors Deficiencies in the quality of dental restorations or prostheses are contributing factors to gingival inflammation and periodontal destruction. Space between the margin of the restoration and the unprepared tooth, the contour of the restorations, the occlusion, the materials used in the restoration, the restorative procedure itself, and the design of the removable partial denture its an important characteristic to maintain periodontal health. Retained Cement and Peri-Implantitis Peri-implantitis is an inflammatory disease of the tissues around dental implants resulting in progressive bone loss.