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On the physicochemistry of plaque calcification and the phase composition of dental calculus (1985)

Driessens, F. C. M. ; Borggreven, J. M. P. M. ; Verbeeck, R. M. H. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Journal of periodontal research 20 (1985), S. 0

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ISSN: 1600-0765

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: The main constituents of human dental calculus are a carbonate containing apatite and a Mg and Zn containing Whitlockite. A third important component is octocalcium phosphate. If the salivary pH is low enough, human dental calculus can also contain dicalcium phosphate dehydrate. According to the physicochemical model of calculus formation, dental calculus must contain calcite as the main component in animals having a high salivary pH.This hypothesis appeared to be valid for a salivary pH of 8 or higher (dogs, miniature pigs, domestic pigs). The physicochemical model implies that resting plaque has certain periods in which it has a higher pH than the saliva and the crevicular fluid in which it is bathed. Literature data provide evidence of such a higher pH, probably caused by proteolysis resulting in the formation of urea, ammonia, and amines by the plaque bacteria. The importance of this mechanism is supported by the fact that protease activity in saliva and dental calculus index are correlated positively (Watanabe et al. 1982). Finally, the importance of saliva as a source of urea and the application of urea rinses in dentistry are discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1600-0765.1985.tb00442.x

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Biological calcium phosphates and their role in the physiology of bone and dental tissues I. Composition and solubility of calcium phosphates (1978)

Driessens, F. C. M. ; Dijk, J. W. E. ; Borggreven, J. M. P. M.

Springer

Calcified tissue international 26 (1978), S. 127-137

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ISSN: 1432-0827

Keywords: Calcium phosphates ; Composition ; Dissolution ; Precipitation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology , Medicine , Physics

Notes: Summary Variations in the composition of bone and tooth mineral are consistent with the model that the constituents are a mixed microcrystalline apatite (AP)-octocalcium phosphate (OCP) like phase and an amorphous or submicrocrystalline calcium phosphate (ACP) like phase whereby these phases can occur in different proportions. An appropriate model for a description of the variable composition and the solubility behavior of the apatite phase is given by the formula $$\begin{array}{*{20}c} {\begin{array}{*{20}c} {Ca_{5 - x - y - u} Na_{\frac{2}{3} y} } \\ {\{ (PO_4 )_{3 - x - y } (CO)_{x + y} \} (H_2 O)_{y + z} OH_{1 - x - \frac{1}{3} y - 2u} } \\\end{array}} \\\end{array}$$ in which the compositional parameters x, y, z, and u each account for one type of defect mechanism. Other point defects are formed as well by incorporation of minority amounts of ions such as Cl−, K+, and F−; a number of trace elements can substitute for Ca2+ ions under in vivo conditions. It is suggested that the incorporation of ions in or loss from the crystals in contact with aqueous solutions is reversible. Literature data are used to show the direction in which the solubility product of the apatite phase shifts by incorporation of the different physiologically relevant ions. A quantitative evaluation of the available literature data revealed that Na+ and CO3 = incorporation is the main cause for shifts in the solubility product of biological apatites.