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Role of the Oral Environment – Introduction
29-03-2010
Role of the Oral Environment Introduction In certain aspects, the oral cavity may be regarded as a single microbial ecosystem. A major regulatory factor is the flow rate of saliva, which decreases to almost 0.0 mL/min during sleep, is approximately 0.4 mL/min at rest, and increases to 2.0 mL/min after stimulation. Although saliva is not a good medium for supporting the growth of many bacteria, 1.0 mL of whole saliva may contain more than 200 million microorganisms, representing more than 300 different species. Most originate from local environments in the oral cavity, but a minority belong to the so-called normal microflora of saliva and obtain nutrients from salivary proteins. All the surfaces of the oral cavity are colonized by microorganisms. The facultatively anaerobic streptococci constitute an essential part of the microflora that constantly colonize the mucous membranes and the teeth. Microorganisms are regularly swallowed with saliva and the amount within the oral cavity fluctuates, simply because the microbial deposits building up on mucous membranes and, in particular, on tooth surfaces grow and multiply, thus providing a reservoir for the oral environment. Fluctuations also occur during sleeping and waking hours, and also as a result of such activities as eating and drinking and oral hygiene procedures. Because the composition of the microflora in mixed saliva is mainly a result of the microorganisms that colonize oral surfaces, the salivary microflora to some extent reflects the gross composition of the microbial deposits on the various oral surfaces. The oral cavity presents two types of surface for colonization by bacteria, the soft tissues and the hard tooth surfaces, modified to some extent by a coating of saliva, or, in the case of the hard surfaces, by a pellicle formed by adsorption of salivary components. A distinct and important difference between the two types of surface is that the soft tissue surfaces are lost when the cells are shed; thus, readherence of bacteria is essential for survival. In contrast to the hard surfaces which will support heavy deposits of bacteria in dental plaque, the soft tissue surfaces do not support formation of complex layers of bacteria (biofilms). It is also likely that microbes attached to desquamated epithelial cells spread, via saliva, to different tooth surfaces and typically colonize sheltered regions: interproximal spaces, gingival margins, and occlusal fissures (Saxton, 1975).
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Articles for theme “caries”:
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29-03-2010
Rate of accumulation (Plaque Formation Rate Index)The quantity of plaque that forms on clean tooth surfaces during a given time represents the net result of interactions among etiologic factors, many internal and external risk indicators and risk factors, and protective factors:· The total oral bacterial population· The quality of the oral bacterial flora· The anatomy and surface morphology of the dentition· The wettability and surface tension of the tooth surfaces· The salivary secretion rate and other properties of saliva· The intake of fermentable carbohydrates· The mobility of the tongue and lips· The exposure to chewing forces and abrasion from foods· The eruption stage of the teeth· The degree of gingival inflammation and volume of gingival exudate· The individual oral hygiene habits· The use of fluorides and other preventive products, such as chemical plaque control agents This observation has been the rationale for the development of the Plaque Formation Rate Index (PFRI) by Axelsson (1989, 1991).
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29-03-2010
Measurement of plaqueAmount of accumulationSeveral indices for recording supragingival plaque have been developed. The two most frequently used are the Plaque Index (PI), developed by Silness and Loe (1964), and O’Leary’s Plaque Index (O’Leary et al, 1972).The Silness and Loe Plaque Index has a four-point scale:· Score 0 = The tooth surface is clean.· Score 1 = The tooth surface appears clean, but dental plaque can be removed from the gingival third with a sharp explorer.
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29-03-2010
According to Dawes et al (1963), dental plaque is “the soft tenacious material found on tooth surfaces which is not readily removed by rinsing with water.” It is estimated that 1 mm3 of dental plaque, weighing about 1 mg, will contain more than 200 million bacteria. Other microorganisms, such as mycoplasma, “yeasts,” and protozoa, also occur in mature plaque; sticky polysaccharides and other products form the so-called plaque matrix, which constitutes 10% to 40% by volume of the supragingival plaque.
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29-03-2010
Dental caries is an infectious, transmissible disease. As early as 1954, Orland et al demonstrated that, although germ-free animals do not develop caries, even with frequent sugar intake, all animals in the group rapidly develop carious lesions when human cariogenic bacteria (mutans streptococci) are introduced in the mouth of one animal. Specific bacteria (acidogenic and aciduric) that colonize the tooth surfaces are recognized as etiologic factors in dental caries. Frequent intake of fermentable carbohydrates, such as sugar, is regarded only as an external (environmental) modifying risk factor or prognostic risk factor.
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16-09-2009
Dental caries
Dental caries – a pathological process, which appears after the dentition, at which the demineralization and softening of dental hard tissues with the subsequent formation of a defect in the form of cavities.
Caries classified:
1. Dental caries in the stage of the spot.
2. Surface caries.
3. The average caries.
4. Deep caries.
Physical methods of diagnosis, treatment and prevention are applied at different stages of the caries process.
When caries in the stage of applying patches reminera-ization of dental tissues using electrophoresis of calcium fluoride.
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