title: Effects of fluoride on in vitro enamel demineralization analyzed by ¹⁹F MAS-NMR.
abstract: The mechanistic action of fluoride on inhibition of enamel demineralization was investigated using (19)F magic angle spinning nuclear magnetic resonance (MAS-NMR). The aim of this study was to monitor the fluoride-mineral phase formed on the enamel as a function of the concentration of fluoride ions [F(-)] in the demineralizing medium. The secondary aim was to investigate fluorapatite formation on enamel in the mechanism of fluoride anti-caries efficacy. Enamel blocks were immersed into demineralization solutions of 0.1 M acetic acid (pH 4) with increasing concentrations of fluoride up to 2,262 ppm. At and below 45 ppm [F(-)] in the solution, (19)F MAS-NMR showed fluoride-substituted apatite formation, and above 45 ppm, calcium fluoride (CaF2) formed in increasing proportions. Further increases in [F(-)] caused no further reduction in demineralization, but increased the proportion of CaF2 formed. Additionally, the combined effect of strontium and fluoride on enamel demineralization was also investigated using (19)F MAS-NMR. The presence of 43 ppm [Sr(2+)] in addition to 45 ppm [F(-)] increases the fraction of fluoride-substituted apatite, but delays formation of CaF2 when compared to the demineralization of enamel in fluoride-only solution.
authors.affiliation: Dental Physical Sciences Unit, Centre for Oral Growth and Development, Barts and The London School of Medicine and Dentistry, Queen Mary University, London, UK.
authors.forename: N R
authors.initials: NR
authors.lastname: Mohammed
authors.forename: N W
authors.initials: NW
authors.lastname: Kent
authors.forename: R J M
authors.initials: RJ
authors.lastname: Lynch
authors.forename: N
authors.initials: N
authors.lastname: Karpukhina
authors.forename: R
authors.initials: R
authors.lastname: Hill
authors.forename: P
authors.initials: P
authors.lastname: Anderson
mesh_terms: D019342:Acetic Acid / Q000009:adverse effects; D001031:Apatites / Q000737:chemistry; D002118:Calcium / Q000032:analysis; D002124:Calcium Fluoride / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry / Q000494:pharmacology*; D011232:Chemical Precipitation; D003743:Dental Enamel / Q000737:chemistry / Q000187:drug effects*; D017886:Durapatite / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry / Q000494:pharmacology*; D005461:Fluorine; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D010758:Phosphorus / Q000032:analysis; D013054:Spectrophotometry, Atomic; D013324:Strontium / Q000494:pharmacology; D017001:Tooth Demineralization / Q000378:metabolism*
chemical_list: D001031:Apatites; D002327:Cariostatic Agents; D010758:Phosphorus; D005461:Fluorine; D017886:Durapatite; C025105:fluorapatite; D002124:Calcium Fluoride; D019342:Acetic Acid; D005459:Fluorides; D002118:Calcium; D013324:Strontium