Transformation of Hydroxyapatite to Fluorapatite

Wier, D. R.; Chien, S. H.; Black, C. A.

doi:10.2136/sssaj1972.03615995003600020024x

Cited by 13 publications

(9 citation statements)

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“…It is possible that the mineral is covered with a thin, maybe monomolecular layer of fluorapatite or fluoridated hy droxyapatite which may not be detectable by the usual physical techniques. How ever, a similar reaction has been observed by Wier et al [1972] applying fluoridecontaining solutions to pure hydroxyapa tite. They observed that after this applica tion the solubility behavior was indistin guishable from that of pure fluorapatite, although the amount of fluoride incorpo rated in the apatite was far less than the theoretical amount of 3.8%.…”

Section: Discussionsupporting

confidence: 64%

Microradiography and Electron Microprobe Analysis of Some Natural White and Brown Spot Enamel Lesions with and without Laminations

Driessens

Theuns²,

Heijligers

et al. 1986

Caries Res

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Extensive ‘white spot’ and ‘brown/white spot’ lesions with intact surfaces in 11 molars were investigated by microradiography and electron microprobe analysis for Fe, Ca, Na and Cl. At the surface of the brown spots some Fe was found. Within the lesions a preferential dissolution of Na and a slight enrichment of Cl was found. This suggests that Na and Cl are sited in different parts of the mineral and the Na-containing part appears to be more soluble. The Na and Cl contents of a lamination approach those of adjacent sound enamel. This indicates that laminations do not result from major reprecipitation of a less soluble calcium phosphate within the formed lesion, but that the mineral is protected from local dissolution early in the process. A possible mechanism is discussed.

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Section: Discussionsupporting

confidence: 64%

Microradiography and Electron Microprobe Analysis of Some Natural White and Brown Spot Enamel Lesions with and without Laminations

Driessens

Theuns²,

Heijligers

et al. 1986

Caries Res

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“…Many minor and trace elements can substitute in the apatite lattice, and the degree of substitution affects the crystal color and lattice stability [51,52]. The elemental compositions of apatite crystals were characterized by ICP-AES (Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Protein-crystal interface mediates cell adhesion and proangiogenic secretion

Weisi

Brian

et al. 2017

Biomaterials

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The nanoscale materials properties of bone apatite crystals have been implicated in breast cancer bone metastasis and their interactions with extracellular matrix proteins are likely involved. In this study, we used geologic hydroxyapatite (HAP, Ca10(PO4)6(OH)2), closely related to bone apatite, to investigate how HAP surface chemistry and nano/microscale topography individually influence the crystal-protein interface, and how the altered protein deposition impacts subsequent breast cancer cell activities. We first utilized Förster resonance energy transfer (FRET) to assess the molecular conformation of fibronectin (Fn), a major extracellular matrix protein upregulated in cancer, when it adsorbed onto HAP facets. Our analysis reveals that both low surface charge density and nanoscale roughness of HAP facets individually contributed to molecular unfolding of Fn. We next quantified cell adhesion and secretion on Fn-coated HAP facets using MDA-MB-231 breast cancer cells. Our data show elevated proangiogenic and proinflammatory secretions associated with more unfolded Fn adsorbed onto nano-rough HAP facets with low surface charge density. These findings not only deconvolute the roles of crystal surface chemistry and topography in interfacial protein deposition but also enhance our knowledge of protein-mediated breast cancer cell interactions with apatite, which may be implicated in tumor growth and bone metastasis.

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“…This relatively slow process (Wier et al, 1972) will undoubtedly occur and cause an increase of the pK of the mineral (pKmin) that is, its solubility decreases. But according to Nelson et al (1983), the effect of fluoride, incorporated into the crystal lattice of synthetic apatites, on the initial rate of dissolution of these apatites was negligibly small, if there was any effect.…”

Section: Discussionmentioning

confidence: 99%

The Demineralization of Human Dental Roots in the Presence of Fluoride

1987

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Intact roots of human molars, which had not been exposed to the oral environment, were exposed to buffer solutions of pH 5.5, which contained, besides calcium and phosphate, various concentrations of fluoride. Densitometric measurements on contact-microradiograms of transverse sections of these roots produced data which were used to calculate the rate of demineralization (Vdem). Vdem appeared to be reduced with increasing fluoride concentration and with decreasing pIOHA (i.e., the negative logarithm of the ionic product of hydroxyapatite) of the buffer solution. In addition, it was observed that, after some days of exposure, remineralization started to occur within the surface layer at some micron from the outer surface and that the region within which remineralization took place was extended inward with increasing time of exposure. These data suggest that fluoride is effective in the prevention of root surface caries. The mechanism of the interaction of fluoride with the root mineral is discussed.

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Transformation of Hydroxyapatite to Fluorapatite

Cited by 13 publications

References 0 publications

Microradiography and Electron Microprobe Analysis of Some Natural White and Brown Spot Enamel Lesions with and without Laminations

Microradiography and Electron Microprobe Analysis of Some Natural White and Brown Spot Enamel Lesions with and without Laminations

Protein-crystal interface mediates cell adhesion and proangiogenic secretion

The Demineralization of Human Dental Roots in the Presence of Fluoride

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