Related Experiment Video
Updated: May 29, 2025
Rapid Mix Preparation of Bioinspired Nanoscale Hydroxyapatite for Biomedical Applications
Published on: February 23, 2017
Effects of fluoride on in vitro hydroxyapatite demineralisation analysed by 19F MAS-NMR
Bajram Ferizoli1, Alexander J Cresswell-Boyes1, Paul Anderson1
1Dental Physical Sciences Unit, Centre for Oral Bioengineering, Institute of Dentistry, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
Introduction:
Fluoride plays a major role in inhibiting enamel dissolution and promoting fluorapatite formation. Porous hydroxyapatite (HAP) discs can be used as an enamel analogue in artificial demineralisation/remineralisation studies.
Method:
The aim of the study was to monitor the fluoride-mineral phases formed on HAP surfaces as a function of fluoride concentration ([F-]) under demineralising conditions, using 19F magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy, and compare the results with a previous study using an enamel substrate. Porous HAP blocks were immersed in demineralisation solutions (0.1 M acetic acid, pH 4.0) with increasing [F-] (0-1450 ppm).
Results:
At below 50 ppm [F-], 19F MAS-NMR showed fluoride-substituted apatite formation; above 50 ppm [F-], calcium fluoride (CaF2) was formed in increasing proportions. These results mirrored those of previous similar studies with an enamel substrate. Further increases in fluoride caused no further measurable reduction in demineralisation but increased the proportion of CaF2 formed. The total calcium concentration [Ca] and total phosphorus [P] concentrations in the solution were measured by inductively coupled plasma atomic emission spectroscopy. At high fluoride concentrations, the solution total [P] increased, and the molar Ca:P ratios decreased to values consistent with the formation of CaF2. However, Ca:P ratios found at low [F-] were higher than those in the previous enamel study and consistent with the formation of a partially fluoridated apatite.
Conclusions:
Under demineralising conditions, CaF2 formed on HAP at an [F-] of 50 ppm and above, whereas fluoridated apatite formed at an [F-] below 50 ppm. The results were consistent with those obtained when an enamel substrate was used.
More Related Videos
09:24Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products
Published on: August 22, 2017
14:55Analysis of Minerals Produced by hFOB 1.19 and Saos-2 Cells Using Transmission Electron Microscopy with Energy Dispersive X-ray Microanalysis
Published on: June 24, 2018
Related Concept Videos
01:16Other Nuclides: 31P, 19F, 15N NMR
While fluorine-19 and phosphorous-31 have high natural abundances (100%) and positive gyromagnetic ratios, nitrogen-15 has a low natural abundance and a negative gyromagnetic ratio. However, nitrogen-15 is still preferred over nitrogen-14 (which has a...
01:31Essential Minerals for Bone Health
Calcium and Phosphorus
Calcium is a critical component of bones, especially in the form of calcium phosphate and calcium carbonate. Since the body cannot make calcium, it must be obtained from the diet. However, calcium cannot be absorbed from the small intestine without...