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Ebook Textbook of oral medicine (2/E): Part 2

Part 2 book “Textbook of oral medicine” has contents: Dental caries, salivary gland disorders, disorders of maxillary sinus, soft tissue calcifications, bacterial infections, viral infections, viral infections, viral infections, metabolic disorders, blood disorders, blood disorders, and other contents. | 516 3 Textbook of Oral Medicine 21 Dental Caries Introduction Dental caries is a microbial disease of the calcified tissues of the teeth, characterized by demineralization of the inorganic portion and destruction of the organic substance of the tooth. It is one of the most common infectious diseases affecting the human race. Cariogenic plaque contains 2 × 108 bacteria per milligram weight and pH of 5.5 is critical threshold for the demineralization. The initial lesion appears as opaque white or brown spot beneath the plaque layer. As the caries process results in demineralization, the affected area of the tooth appears more radiolucent than unaffected area. Carious area attenuates less radiation than intact tooth substance so that the area of the film on which remnant beam from the deminerlized area falls, it receives higher exposure and thus appears more darker on the processed radiograph. The disease process begins with the concentration of Streptococcus mutans at specified tooth surfaces and lead to white spot formation or even cavitations. The development of dental caries is a dynamic process of demineralization of the dental hard tissues by the products of bacterial metabolism, alternating with periods of remineralization. Etiology • Dietary factor—carbohydrates with types like monosaccharides, disaccharides or polysaccharides and the amount consumed and whether it is between meals. • Microorganisms—acidogenic Streptococcus mutans and Actinomycosis viscosus. • Systemic factors—hereditary, pregnancy and lactation factors have been suggested as etiological factors for dental caries. • Host factor—poor oral hygiene and improper brushing technique can lead to dental caries. • Immunological factor—the functional role of circulating antibodies as protective agents against tooth decay has been demonstrated in non-human primates. Pathogenesis • Fermentation of oral microorganism—whenever carbohydrate is consumed, oral microorganisms rapidly begin fermentation