PubMed · 268368
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R C Abrahamson. 1977. Correction on fluoride content.. https://doi.org/10.14219/jada.archive.1977.0455
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Fluoridated hydroxyapatites were synthesized with two different modes of fluoride supply: by supplying F(-)-free solution initially, followed by a F(-)-containing solution whose fluoride concentration was stoichiometrically equal to that of fluorapatite; and with the order of supply of these solutions reversed. Both of these heterogeneously synthesized fluoridated hydroxyapatites showed typical calcium phosphate X-ray diffraction patterns; and both had similar total fluoride contents (0.94 +/- 0.02 and 0.99 +/- 0.03 mmol/g, respectively), i.e. half of the maximum fluoride content of fluorapatite. However, they differed considerably in their physico-chemical properties. The former had a wider peak breadth of X-ray diffraction and a lower apparent solubility (Ca = 12.2 +/- 0.7 mmol/l) than the latter (Ca = 19.8 +/- 0.4 mmol/l) at 37 degrees C and pH 4.0. Wavelength dispersive spectroscopy attached to scanning electron microscopy gave clearly different spectra. Electron spectroscopy for chemical analysis of apatite pellets made by pressing and heating showed a slightly larger F1s signal at the crystal surface of the former, although the difference was not marked. These results suggest that two different types of heterogeneous fluoridated hydroxyapatites were formed, hydroxyapatite covered with fluorapatite and fluorapatite covered with hydroxyapatite.
Streptococcus mutans T8 was grown glucose-limited at pH 7.0 in a chemostat and pulsed, under pH free-fall conditions, with glucose, xylitol or a mixture of the two. Experiments were conducted in the absence or continual presence of low levels (1 mmol.l-1) of fluoride. Culture filtrates of samples taken at frequent intervals were assayed for carbohydrate and fermentation end-products. Fluoride had little effect on the organism's response to glucose until the culture pH fell to ca. 5.0, at which point the rate of lactate production was reduced some 3-fold. Xylitol affected the response to glucose but its effect was most marked in the presence of fluoride. Under these conditions, the rate of lactate production was reduced at least 3-fold, the pH did not fall to 5.0 and only about 50% of the added glucose was consumed. This suggests that xylitol can augment the metabolic effects on S. mutans of low levels of fluoride.
The pharmacology of fluoride is reviewed. Efficacy criteria of sodium fluoride in osteoporosis are analysed. An increase in bone mass of the order of 8 per cent per year is seen in 60-70 per cent of osteoporotics whether evaluated by histomorphometry or by bone densitometry in double-blind controlled trials. Fluoride has no effect on bone mass in 30 to 40 per cent of osteoporotics. The reason(s) for such resistance is/are not fully understood. It is not possible at present to state that there is a decrease in the incidence of vertebral fractures on the basis of data from double-blind trials. The incidence of bone fissures affecting the bones of the lower limbs is significantly increased in osteoporotics treated with fluoride, above all if doses of elemental fluoride are greater than 25 mg or in the presence of unrecognised renal insufficiency. The incidence of these fissures is of the order of 20 to 30 per cent.