THEORIES OF DENTAL CARIES - CAUSES AND ETIOLOGY
Following are some of the causes that is believed to cause dental caries..
Chemical (acid) theory.
Parmly (1819) proposed that an unidentified “chymical agent” was responsible for caries. According to this theory, teeth are destroyed by the acids formed in the oral cavity by the putrefaction of protein which produced ammonia and was subsequently oxidized to nitric acid. Robertson (1895) proposed that dental decay was caused by acids formed by fermentation of food particles around teeth.
Parasitic or septic theory.- stated that microorganisms can have toxic and destructive effects on dental tissues. Ficinus ,a dental physician implied that filamentous microorganisms (denticolae) in the enamel cuticle and in carious lesions caused decomposition of the enamel and dentin.
Chemo – parasitic theory. ( W.D. Miller)-
is a blend of chemical and parasitic theory, because it states that caries is caused by acids produced by microorganisms of the mouth. According to this theory,microorganisms of the mouth, by secretion of enzymes or by their own metabolism, degrade fermentable carbohydrate food materials to form acids which demineralizes the enamel and the disintegrated enamel is subsequently mechanically removed by force of mastication. Miller summarized his theory as follows.- Dental decay is a chemoparasitic process consisting of 2 stages- decalcification or softening of the tissue and dissolution of the softened residue.
Proteolytic theory (Gottileb- 1947) -
proposed that microorganisms invade the organic pathways ( lamellae) of the enamel and initiate caries by proteolytic action. Subsequently, the inorganic salts are dissolved by acidogenic bacteria.
Pincus(1950) stated that initial caries process in dental caries was due to the proteolytic breakdown of the dental cuticle.
Proteolysis chelation theory
proposed by Shalz etal implies a simultaneous microbial degradation of the organic components (proteolysis) and the dissolution of the minerals of the tooth by the process of chelation. According to this theory, dental caries results from an initial bacterial and enzymatic proteolytic action on the organic matter of enamel without preliminary demineralization. This cause the release of a variety of complexing agents, such as aminoacids , polyphosphates and organic acids which then dissolve the crystalline apatite.
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