Calculus
Dental Calculus consists of mineralized bacterial plaque that forms on the surfaces of natural teeth and dental prosthesis. [Carranza ]Mineralized dental plaque that is permeated with crystals ofvarious calcium phosphates Calculus is also known as odontolithiasis or tartar. It is alsocalled fossilized plaque.
Dental calculus is classified by its location on a tooth surface as related to the adjacent free gingival margin:
SUPRAGINGIVAL CALCULUSLocation –On the clinical crown coronal to the margin of the gingiva andvisible in the oral cavity.Distribution –Most frequent sites are on the lingual surfaces of the mandibularanterior teeth opposite Warton’s duct and on the buccal surfacesof the maxillary molars opposite Stenson’s duct.Crowns of teeth out of occlusion; non-functional; or teeth thatare neglected during daily plaque removal.Surfaces of dentures and dental prosthesis.
SUBGINGIVAL CALCULUS Location- *On the clinical crown apical to the margin of the gingiva, usually in periodontal pockets, not visible upon oral examination. *Extents to bottom of the pocket and follows contour of soft tissue attachment.
Sub-gingival calculus is located below the crest of the marginal gingiva and therefore not visible on routine clinical examination, the location and extent of the sub-gingival calculus may be evaluated by careful tactile perception with a delicate dental instruments such as a dental explorer, sub-gingival calculus is typically hard and dense, frequently appears dark brown or greenish black in color firmly attached to the tooth surface. When the gingival tissue recede, sub-gingival calculus become exposed and it's therefore classified as supra-gingival, a reduction in the gingival inflammation and probing depths with a gain in clinical attachment can be observed after the removal of sub-gingival plaque and calculus.
Hanadi Baeissa
*found nearly 100% in mandibular anterior teeth, decreasing posteriorly to 20% of the third molars. In maxilla, 10% of the anterior teeth and 60% of first molars had supragingival calculus.
Inorganic content: supra-gingival calculus consist of inorganic (70% to 90%) and organic components (20-3o%) , 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.
CRYSTALSAtleast two thirds of the inorganic component is crystalline instructure.Electron microscopy & x-ray diffraction studies,4 distinctphosphate crystals :*Hydroxyapatite Ca10(OH)2(PO4)6 – approximately 58%*Magnesium whitlockite Ca9(PO4)6XPO4 - 21%*Octacalcium phosphate Ca4H(PO4)3.2H2O - 12%*Brucite CaHPO4.2H2O - 9%
Brushite is more common in the mandibular anterior region and magnesium white-lockite is in the posterior areas, the incidence of the four crystals varies with the age of the deposit.
Attachment of calculus to the tooth: Attachment by means of organic pellicle. Mechanical inter locking between the surface irregularities such as resorption lacunae and caries. Penetration of calculus bacteria into cementum. Close adaptation of calculus under surface dispersions to the gently sloping mounds of the unaltered cementum surface.
FACTORS AFFECTING THE RATE OF CALCULUSFORMATION*Diet and nutrition –*Increased calculus formation has been associated withdeficiencies of vitamin A, and with anincrease in dietary calcium, phosphorus, bicarbonate,protein and carbohydrate.
*Age – there is an increase in calculus deposition with an increasing age.*This may be due to change in quantity and quality of saliva with age, favouring the mineralization properties.
Habits – In populations that practice regular oral hygiene and with access to regular professional care have low for calculus formation.*Smoking- is associated with an elevated risk for supragingival calculus deposition. Smoking may exert its influence systemically (elevated levels of salivary calcium and phosphorus) or locally via a conditioning of tooth .surfaces
*Salivary pH- increase pH increases the calculus formation. *When the calcium phosphate crystals in solution are in kinetic equilibrium, the rate of precipitation is equal to that of dissolution. *If pH in solution drops (the concentration of hydrogen ions increases), OH- and (PO4)3 - tend to be removed by H+ by forming water and more acidic forms of phosphate, respectively
Dental calculus
Supragingival Friable Readily removed by scaling Unpigmented Form in greatest amounts on the lower incisors & upper molars i.e. near the orifices of the main salivary ducts Composition varies in different sites Salivary originb) Subginival Harder Coloured (often green) Present in smaller deposits, which are not localized near the salivary ducts Composition less site dependent non-salivary (serum) origin
Theories regarding the mineralization of calculus : The theoretical mechanisms by which plaque becomes mineralized can be stratified into two categories:
Mineral precipitation results from a local rise in the degree of saturation of calcium and phosphate irons
Seeding agents induce small foci of calcification that enlarge and coalesce to form a calcified mass. This concept has been referred to as the epitactic concept or more appropriately, hetero-geneous nucleation. The seeding agents in calculus formation are not known, but it is suspected that the intercellular matrix of plaque plays an active role.
Notes: Calculus is higher in smokers. There is variation between different people in amount of calculus formed First stage of calculus formation (matrix deposition) occurs readily in both slow and rapid calculus formers The difference lies in the power to mineralize the matrix
Periodontal Disease Two most frequently occurring forms:
1- Gengivitis2- Periodontitis
Limited to the gingival or soft tissues, surrounding the teeth Results in bleeding of gums, and possibly change in color, shape, size, surface texture and consistency Reversible on restoration of hygiene, does not result in destruction of tissues supporting the teeth
Extension of the inflammatory process from the gingival to the supporting periodontal tissue & destruction of these tissues Can be controlled but not reversed Chronic peridontitis result in loss of bone supporting the teeth mobility tooth loss