Tooth hydroxyapatite

Phosphoromonofluoridates in solution will give a precipitate with silver nitrate (5.277). The sodium and stannous salts (5.278) are used in toothpaste formulations to inhibit dental caries. They act by converting the tooth hydroxyapatite into the somewhat harder and more acid-resistant fluor-... 

Various formulations for dental treatment incorporate polymerised phosphonates, which offer certain advantages over phosphates (Section 12.13). Polyvinyl phosphonic add (12.157) and polyethylene phosphonate (12.159) are adsorbed as monolayers on tooth enamel where they resist decay [29]. Copolymers of vinylphosphonic acid and vinylphosphonyl fluoride (12.201) are also adsorbed on tooth surfaces and provide extra resistance to decay by slowly releasing F which can substitute in the tooth hydroxyapatite [30]. 

When freshly mixed, the carboxyHc acid groups convert to carboxjiates, which seems to signify chemical adhesion mainly via the calcium of the hydroxyapatite phase of tooth stmcture (32,34—39). The adhesion to dentin is reduced because there is less mineral available in this substrate, but bonding can be enhanced by the use of minerali2ing solutions (35—38). Polycarboxylate cement also adheres to stainless steel and clean alloys based on multivalent metals, but not to dental porcelain, resin-based materials, or gold alloys (28,40). It has been shown that basic calcium phosphate powders, eg, tetracalcium phosphate [1306-01-0], Ca4(P0 20, can be substituted for 2inc oxide to form strong, hydrolytically stable cements from aqueous solution of polyacids (41,42). 

Tooth enamel is a hydroxyapatite, Ca5(P04)30H. Tooth decay begins when acids attack the enamel ... 

C03-0084. Tooth enamel is composed largely of hydroxyapatite, which has the following mass percent... 

Aluminium ions released from the dental silicate cement are also absorbed by hydroxyapatite and have a similar beneficial effect to that of fluoride (Halse Hals, 1976 Putt Kleber, 1985). Thus, the dental silicate cement confers protection against caries (dental decay) on surrounding tooth material. 

CCP in milk is mentioned in connection with casein above (Section VI.C). Fluorapatite is a major constituent of phosphate rocks, and a constituent, probably important, of human tooth enamel for those whose drinking water contains significant amounts of naturally occurring or added fluoride. Fluorapatite is significantly less soluble than hydroxyapatite - the relationship between the solubilities of fluorapatite and hydroxyapatite parallels (but is much less extreme than) that between calcium fluoride (Ksp — 3.9 x 10 11 mol3 dm-9) and calcium hydroxide (Ksp = 7.9 x 10 6 mol3 dm 9). Calcium diphosphate, Ca2P207, is believed to be the least soluble of the calcium phosphates. 

Most calcium, containing apatites in nature are heavily carbonated. The only exception is formed by the mineral in the surface of tooth enamel which consists mainly of hydroxyapatite (Ca5(P04)30H). 

Sugar is a common ingredient in prepared foods. When sugar remains on your teeth, bacteria in your mouth convert it into an acid. The principal constituent of tooth enamel is a mineral called hydroxyapatite, Caio(P04)6(OH)2. Hydroxyapatite reacts with acids to form solvated ions and water. (Solvated ions are ions surrounded by solvent particles.) Eventually, a cavity forms in the enamel. 

Interest in the nature of interactions between shortchain organic surfactants and large molecular weight macromolecules and ions with hydroxyapatite extends to several fields. In the area of carles prevention and control, surfactant adsorption plays an important role in the Initial states of plaque formation (1-5) and in the adhesion of tooth restorative materials ( ). Interaction of hydroxyapatite with polypeptides in human urine is important in human biology as hydroxyapatite has been found as a major or minor component in a majority of kidney stones ( 7). Hydroxyapatite is used in column chromatography as a material for separating proteins (8-9). The flotation separation of apatite from... 

Humic substances. Analogous to the reactions described above, humic substances (the polymeric pigments from soil (humus) and marine sediments) can be formed by both enzymatic and non-enzymatic browning. High concentrations of free calcium and phosphate ions and supersaturation with respect to hydroxyapatite can sustain in soil, because adsorption of humic acids to mineral surfaces inhibits crystal growth (Inskeep and Silvertooth, 1988). A similar adsorption to tooth mineral in a caries lesion can be anticipated for polycarboxylic polymers from either the Maillard reaction or enzymatic browning. 

Chlorhexidtne is a symmetrical cationic molecule that is most stable as a salt the highly water-soluble digluconate is the most commonly used preparation. Because of its cationic properties, it binds strongly to hydroxyapatite (the mineral component of tooth enamel), the organic pellicle on the tooth surface, salivary proteins, and bacteria. Much of the chlorhexidine binding in the mouth occurs on the mucous membranes, such as the alveolar and gingival mucosa, from which sites it is slowly released in active form. 

The various findings about fluoride and its interaction with the hydroxyapatite at the molecular level show that the relationship is complicated and multifaceted. The broad conclusion from the enormous volume of work that has led to our current understanding of the role of fluoride is that it is overwhelmingly beneficial. It promotes numerous desirable properties in tooth mineral, reducing solubility through action in both the saliva and in the mineral phase, it shifts the demineralisation/remineralisation equilibrium in favour of remineralisation, and through its actions in the solid state, ensures that the kinetically favoured OCP is transformed into the more thermodynamically stable hydroxyapatite. Research continues, and there is no doubt that there is still more to learn about the complexities of the interaction of fluoride with hydroxypatite under physiological conditions. 

More recently, it has been shown that topical fluoride preparations do not lead to fluoridation of the hydroxyapatite crystal [181]. Rather they form a calcium fluoride-like substance that is deposited onto the tooth surface and dissolves when the local pH is lowered [182]. The resulting dissolution adjacent to the tooth surface provides a source of soluble fluoride that can be incorporated into the mineral structure, and thus augment remineralisation. 

Anti-adhesive effect. Green and roasted coffee, used in a treatment mixture and as a pretreatment on beads, inhibited the Strep tococcus mutans sucrose-independent adsorption to saliva-coated hydroxyapatite beads. The inhibition of Salmonelb mutans adsorption indicated that coffee-active molecules may adsorb to a host surface, preventing the tooth receptor from interacting with any bacterial adhesions. Among the known tested coffee components, trigonelline and nicotinic and chlorogenic acids are very... 

Another example is LIBS application for real-time identification of carious teeth (Samek et al. 2003). In the dental practice, usually more healthy tissue is removed than ultimately necessary. Carious and healthy tooth material can be identified through the decrease of matrix elements Ca and P in hydroxyapatite and/or the increase of non-matrix elements, typically Li, Sr, Ba, Na, Mg, Zn and C, using pattern recognition algorithms. A fiber-based LIBS assembly was successfully used for this task. As for the case of phosphate ores evaluation, the efforts aimed at normalizing the spectrum collection conditions and procedures, so that the spectra are sufficiently reproducible for precise quantitative... 

Misra, D. N., Bowen, R. L. Wallace, B. M. 1975. Adhesive bonding of various materials to hard tooth tissues. VII nickel and copper ions on hydroxyapatite role of ion exchange and surface nuclea-tion. Journal of Colloid and Interface Science, 51, 36-43. 

When studying a complex material such as tooth enamel it is invaluable to have accurate data on single crystals of the apatite of which it comprised. Figure 9.16(a) is a V(z) curve measured using a line-focus-beam microscope at 225 MHz, on the biggest crystal of hydroxyapatite in the world At least 12... 

Fluoride ion tends to replace the isoelectronic ion OH- in solids. In particular, hydroxyapatite, Cas O OH, the chief constituent of tooth enamel, reacts slowly with aqueous fluoride to form fluoroapatite, which is harder and more resistant to tooth decay. The dental profession therefore advocates fluoride treatments at the time of regular dental checkups, and also (primarily to provide for the dental health of children) the presence of 0.7-1.0 ppm natural or added F in drinking water. Too much (>4 ppm) F in water, however, is acknowledged to cause mottling of teeth and bone sclerosis. Thus, the range of concentrations over which fluoride in public drinking water is considered to be beneficial is rather narrow. 

Signal D gD = 1.9973 = g (orthorhombic C02 ) The orthorhombic and axial C02 molecular ions were detected in CaC03 and NaHC03 (nahcolite) as well as in hydroxyapatite (tooth enamel)... 

An important example of the effect of pH on solubility is tooth decay. Tooth enamel contains the mineral hydroxyapatite, which is insoluble near neutral pH, but dissolves in acid because both phosphate and hydroxide in the hydroxyapatite react with H+ ... 

Bacteria on the surface of our teeth metabolize sugars to produce lactic acid, which lowers the pH enough to slowly dissolve tooth enamel. Fluoride inhibits tooth decay because it forms fluorapatite, Cal0(PO4)6F2, which is more acid resistant than hydroxyapatite. 

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