Effects of fluoride on in vitro hydroxyapatite demineralisation analysed by 19F MAS-NMR

Introduction Fluoride plays a major role in inhibiting enamel dissolution and promoting fluorapatite formation. Porous hydroxyapatite (HAP) discs can be used as an analogue artificial demineralisation/remineralisation studies. Method The aim of the study was to monitor fluoride-mineral phases formed on HAP surfaces function fluoride concentration ([F − ]) under demineralising conditions, using 19 F magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy, compare results with previous substrate. blocks were immersed demineralisation solutions (0.1 M acetic acid, pH 4.0) increasing [F ] (0–1450 ppm). Results At below 50 ppm ], MAS-NMR showed fluoride-substituted apatite formation; above calcium (CaF 2 ) proportions. These mirrored those similar studies Further increases caused no further measurable reduction but increased proportion CaF formed. total [Ca] phosphorus [P] concentrations solution measured by inductively coupled plasma atomic emission spectroscopy. high concentrations, increased, molar Ca:P ratios decreased values consistent formation . However, found at low higher than partially fluoridated apatite. Conclusions Under above, whereas ppm. obtained when substrate used.