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Formation of brushite, monetite and whitlockite during equilibration of human enamel with acid solutions at 37C


Shellis, RP and Heywood, BR and Wahab, FK, Formation of brushite, monetite and whitlockite during equilibration of human enamel with acid solutions at 37 C, Caries Research, 31, (1) pp. 71-77. ISSN 0008-6568 (1997) [Refereed Article]

DOI: doi:10.1159/000262377


The residues of 5 samples of powdered human enamel, each subjected to 5 sequential equilibrations at 37C with either 17 or 4 mmol/1 phosphoric acid, were examined microscopically. With 17 mmol/1 acid, both brushite and monetite were found after 1 equilibration but, after further equilibrations, brushite was no longer present and the abundance of monetite crystals increased. Formation of monetite probably contributed to the lower metastability of this system compared to similar low-pH systems at 25 C, where monetite does not form. Neither brushite nor monetite were present after equilibration with 4 mmol/1 acid. Whitlockite was identified by transmission electron microscopy and electron diffraction in all residues. In the 4 mmol/1 systems, the ionic activity product (IMwH) for magnesium whitlockite, Ca9Mg(HPO4)(PO4)6, became constant after 1-3 equilibrations, at a mean value of 3.6 (0.51 SE)10-105, which may reflect saturation with respect to this solid. For the 17 mmol/1 systems, higher values of IMWH, and supersaturation with respect to monetite, were interpreted as evidence for persistent metastability due to slow crystal growth of whitlockite and monetite. It is concluded that neither brushite nor monetite are likely to form within carious lesions, but the results are consistent with the known association of whitlockite with caries.

Item Details

Item Type:Refereed Article
Keywords:apatite, brushite, enamel, monetite, solubility, whitlockite
Research Division:Biological Sciences
Research Group:Biochemistry and cell biology
Research Field:Structural biology (incl. macromolecular modelling)
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the biological sciences
UTAS Author:Heywood, BR (Professor Brigid Heywood)
ID Code:104443
Year Published:1997
Web of Science® Times Cited:29
Deposited By:Research Division
Deposited On:2015-11-11
Last Modified:2015-11-12

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