Dental plaque fluid

Y.P. Zhang, R.L. Kent Jr., H.C. Margolis, Enamel demineralization under driving forces found in dental plaque fluid, Eur. J. Oral Sci. 108 (2000) 207-213. 

Carey C, Gregory T, Rupp W, Tatevossian A, Vogel GL The driving forces in human dental plaque fluid for demineralisation and remineralisation of enamel mineral in Leach S (ed) Factors Relating to Demineralisation and Remineralisation of the Teeth. Oxford, IRL Press, 1986, pp 163-173. 

Gao XJ, Fan Y, Kent RL Jr, Van Houte J, Margolis HC Association of caries activity with the composition of dental plaque fluid. J Dent Res 2001 80 1834-1839. 

Bacterial catabolism of oral food residue is probably responsible for a higher [NHj] in the oral cavity than in the rest of the respiratory tract.Ammonia, the by-product of oral bacterial protein catabolism and subsequent ureolysis, desorbs from the fluid lining the oral cavity to the airstream.. Saliva, gingival crevicular fluids, and dental plaque supply urea to oral bacteria and may themselves be sites of bacterial NH3 production, based on the presence of urease in each of these materials.Consequently, oral cavity fNTi3)4 is controlled by factors that influence bacterial protein catabolism and ureolysis. Such factors may include the pH of the surface lining fluid, bacterial nutrient sources (food residue on teeth or on buccal surfaces), saliva production, saliva pH, and the effects of oral surface temperature on bacterial metabolism and wall blood flow. The role of teeth, as structures that facilitate bacterial colonization and food entrapment, in augmenting [NH3J4 is unknown. 

The levels of fluoride in body fluids (plasma, saliva, urine) give some indication of recent fluoride intake. Fluoride ion does not produce any metabolites, and so is itself the measured indicator. This indicator, however, does not well reflect the fluoride body burden or the accumulation of fluoride in the body, because the relation between fluoride concentrations in bone and in extracellular fluids is incompletely defined. The concentration of fluoride in plasma, urine, saliva and dental plaque is dependent on the intake via water, diet, fluoride supplements and fluoride-containing dentifrices [92-97],... 

In general, saliva (as well as plaque fluid) is supersaturated with respect to calcium-phosphate salts, and they prevent tendency to dissolve mineral crystals of teeth. Moreover, precipitation of calcium-phosphate salts that include hydroxyapatite may also occur (remineralization) in early lesions of tooth surfaces injured by acidic bacterial products (i.e., lactic acid). Salivary fluoride facilitates calcium-phosphate precipitation, and such crystals (i.e., fluorapatite) show lower acid solubility properties that lead to an increased caries preventive effect. The increase of pFI (i.e., buffer capacity and pH of saliva, as well as ureolysis in dental plaque) also facilitates crystal precipitation and remineralization (4, 13). 

De- and remineralisation are two dynamic processes of dental caries, in which chemical composition plays a key role. The driving force for de- and remineralisation of tooth mineral is the degree of saturation (DS) with respect to dental minerals in adjacent liquid, i.e. plaque fluid in the caries situation. 

In the context of a chapter on plaque as a reservoir for active ingredients, plaque structure has an important influence on the penetration and clearance of such materials and also of various other species involved in the caries process. We have discussed in previous sections the thermodynamic approach to caries susceptibility adopted by Margolis et al. [1,4-5] that focuses on calculations of the DS of the plaque fluid with respect to dental enamel based on extensive chemical analyses of plaque samples. Dawes, Dibdin and their co-workers [12-19], on the other hand, have modelled essentially the kinetics of the saliva-plaque system to compute Stephan curves within plaque and at the enamel surface following sucrose exposure. Sucrose (and related highly water-soluble species such as glucose) strictly speaking are not retained in plaque, but are either rapidly cleared from the mouth by saliva or converted to other molecules by plaque bacteria. The H+ ions that determine pH are one product of such conversion processes and are retained to an extent. 

The important role of plaque as a reservoir for active agents, such as fluoride from dental products and calcium and phosphate from saliva, is reviewed in Chapter 6. Recent findings on the dependence of the concentration and retention of these agents on plaque location are included. The relationship between plaque fluid chemistry and tooth mineral is the key to caries formation and control. This interdependence is also discussed in Chapter 3. Here both the thermodynamic approach of Margolis and coworkers and the kinetic approach of... 

When biomaterials come into contact with various biological fluids (blood, saliva, tears) protein adsorption at the solid-liquid interface is the first phenomenon which occurs. This primary adsorption process then exerts a profound influence over subsequent events and me y give rise to such well recognized and undesired processes as thrombus formation, formation of dental plaque or dry spot formation in the case of contact lenses. 

Dental calculi, i.e. calcifications of the dental plaque biofilm, contain various calcium phosphates, since these inorganic ions are provided by saliva or crevicular fluids. Although the pattern of calcification of oral microorganisms, either intra- or extracellularly, is mainly a characteristic of each bacterial species or strain [75], it may be influenced by nutritional factors, such as saliva proteins, as well [76]. The interactions of saliva with dental calculi and its role in preventing dental caries by controlling the enamel de- and remineralisation processes have been reviewed [19]. 

Dynamic interactions between the saliva, diet and oral bacteria lead to the accumulation of material on the tooth surface. This is known as dental plaque which can be defined as the deposit which forms on the tooth in its natural environment and, unlike food debris, cannot be removed by a water spray. It is composed of localized concentrations of bacteria specific to this surface together with some degraded mammalian cells. These are surrounded by a matrix containing both protein and polysaccharide and the whole is bathed in a fluid derived from the saliva. On this basis, plaque can be said to have the characteristics of a simple tissue. 

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