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Saturday, December 29, 2007

Clinical manifestations of the dental caries

Saturday, December 29, 2007

The enamel caries is manifested as a white spot where the enamel looses its gloss. It may be brown colored by deposition of a pigment. It is not painful. A large carious defect, extending to a various depth into dentine, is usually painful when a tooth is irritated directly (mechanical, chemical, thermal effects). Pain is relieved, however, immediately after the causing effect stops. The affected tooth has clinical signs of rough surfaces or sharp-edged cavities which may accumulate food residues.


The caries close to the pulp is a result of further progression of the carious process. Dental pulp defends itself by producing the tertiary and transparent dentine. The tertiary dentine is synthesized as a response of odontoblasts to an irritation and it contains more of the basal substance and less dentine tubules. The transparent dentine is made of mineralized processes of odontoblasts. The pulp does not usually display any signs of inflammation and a patient may not have heavy problems. Pain caused on cold, salty, sweet and sour irritation is often reported, however, this pain is relieved after the causing effect stops.


Caries close to the pulp are treated by the method of indirect pulp capping . This treatment is based on supporting the pulp’s resistance by calcium hydroxide (Calxyd brand) that is applied to the pulpal wall of a prepared cavity after soft dentine has been removed. Calxyd has antimicrobial and anti-inflammatory effects and stimulates the pulp’s resistance mechanisms. The Ca2+ and OH- ions penetrate the pulp. OH- ions cause coagulation of protein components of the pulp and neutralize acidic inflammation products. Ca2+ ions stimulate phagocytosis, decrease permeability of capillaries and upon reaction with CO2 form calcium carbonate in the tissue. A layer of Calxyd is covered by the zinc oxide -an eugenol based cement that has good insulation properties, a weak antimicrobial action and stimulates production of the tertiary dentine. This kind of treatment provides for successful results in up to 90% cases. Failures are usually accounted to a false diagnosis, caused by leaving a rather thick layer of softened dentine, or low resistance abilities of the pulp. In cases when the pulp chamber is exposed either by an injury or by careless preparation of a cavity, the direct pulp capping method is indicated. Here, the most appropriate material is calcium hydroxide (Calxyd) as well. This material is applied directly on the exposed pulp providing a perforation is not too large. By these means, a layer of a coagulation necrosis is formed, and the layer of a connective tissue barrier forms underneath it. Non-differentiated mesenchymal cells produce new odontoblasts that differentiate further. A dentine bridge is gradually formed above the perforation which takes 4 to 6 weeks. The success rate of this method is 80%-90%. Failures may be caused by too large a perforation, by infecting the dental pulp, or decrease of the pulp’s immunity.



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