Diffusion of Monofluorophosphate in Whole Bovine Enamel at pH 7
- 1 January 1981
- journal article
- research article
- Published by S. Karger AG in Caries Research
- Vol. 15 (5) , 363-368
- https://doi.org/10.1159/000260539
Abstract
The diffusion of 32P–FPO32–– ions in whole bovine enamel from Na2FPO3 and radioactive tracer 32P–FPO32–– containing solutions was investigated at pH = 7.0 and 37 °C. Various diffusion times (2 and 7 days) and monofluorophosphate (FPO32––) concentrations (1 and 10 mM) were applied. Diffusion profiles have been obtained by the method of serial sectioning of the enamel. A diffusion coefficient Dk = (1.7 ± 0.4) × 10––13cm2s––1 for fast diffusion between the prisms and a diffusion coefficient Dv = (1.8 ± 0.6) × 10––18 cm2s––1 for slow diffusion into the prisms were calculated. The 32P-MFP diffusion profiles are different from similar profiles for phosphate ions, particularly for diffusion distances of less than 20 μm from the enamel surface. The diffusion coefficient for the fast diffusion of the MFP ion is about three orders of magnitude smaller than the diffusion coefficient for the fast diffusion of the fluoride ion. It is concluded that at neutral pH values MFP in enamel is transported in the form of FPO32–– ions.Keywords
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