Effect of fluoride

Because of the corrosive effects and discomfort associated with inhalation of fluorine, chronic toxicity does not occur. Although the metaboHc fate of fluorine is not clear, it does not seem that much is converted to fluoride ion in the body (107). Therefore comparisons to effects of fluoride ion poisoning, known as fluorosis, are probably incorrect. 

Fluorid ions stimulate bone formation by a direct mitogenic effect on osteoblasts mediated via protein kinase activation and other pathways. Further to these cellular effects, fluorides alter hydroxyapatite crystals in the bone matrix. In low doses, fluorides induce lamellar bone, while at higher doses abnormal woven bone with inferior quality is formed. The effect of fluorides on normal and abnormal (e.g. osteoporotic) bone therefore depends on the dose administered. 

The effect of fluoride was further demonstrated by the increase in plutonium solubility in deionized water from about 11 percent to essentially 100 percent by addition of sufficient NaF to raise the fluoride concentration to that of basalt ground water. It is likely that the enhanced solubility of plutonium in waters containing high fluoride concentrations is the result of stabilization of Pu(IV) in solution by formation of fluoride complexes. Normally Pu(IV) is the least soluble of the four... 

Hudis and Wahl have examined the effect of fluoride ion on the exchange rate and have found it necessary to include three fluoride exchange paths... 

Table 5.13. Effect of fluorides on glass polyalkenoate cement compressive strength, MPa (Crisp, Merson < Wilson, 1980)...

Hamilton, I. R. (1977). The effects of fluoride on enzymatic regulation of bacterial carbohydrate metabolism. Caries Research, 11 (Supplement 1), 321-7. 

Turner, R. T., Francis, R., Brown, D., Garand, J., Hannon, K. S. Bell, N. H. (1989). The effects of fluoride on bone implant histomorphology in growing rats. Journal of Bone Mineralogy Research, 4, 477-84. 

McClurg, T.P 1984. Effects of fluoride, cadmium and mercury on the estuarine prawn Penaeus indicus. Water SA 10 40-45. 

Wilkinson, K. J., Campbell, P. G. C. and Couture, P. (1990). Effect of fluoride complexation on aluminum toxicity towards juvenile atlantic salmon (Salmo salar), Can. J. Fish. Aquat. Sci., 47, 1446-1452. 

Many other dietary factors have been reported to affect calcium bioavailability. Phytate, fiber, cellulose, uronic acids, sodium alginate, oxalate, fat (only in the presence of steatorrhea), and alcohol have been reported to decrease calcium bioavailability (15). Lactose and medium chain triglyceride increase it (15). FTuoride also affects calcium retention primarily by stimulating bone formation thereby decreasing calcium excretion (33-38). The effects of fluoride on calcium utilization have been variable (34,38,39). 

Based on limited epidemiologic evidence, fluoride supplements, with or without calcium, estrogen and vitamin D, are used by clinicians for the treatment of osteoporosis. However, knowledge of the effects of fluoride on calcium and phosphorus metabolism in normal animals is limited although Spencer et al. (32) reported that ingestion of fluoride by three osteoporotic men did not affect calcium absorption but caused a decrease in urinary excretion. Moreover, there is a need to determine the long-term effects of fluoride treatment on bone strength and on soft tissues ( ). 

Table IV. Effect of fluoride on bone composition and strength...

Table V. Effect of fluoride on soft tissue levels...

In extensive studies of the effect of fluoride In patients with osteoporosis carried out In this Research Unit, a therapeutic dally dose of 45 mg fluoride per day was used as sodium fluoride. The main effect of fluoride on calcium metabolism was a decrease of the urinary calcium, while the fecal calcium did not change and the calcium balance also remained unchanged. Also, the Intestinal absorption of calcium remained unchanged during the high fluoride Intake (Table I), The decrease In urinary calcium, Induced by sodium fluoride, may be due to decreased bone resorption, a very desirable effect for patients with osteoporosis. 

In conclusion, the solubility data indicate that upon precipitation from aqueous solutions which have a F/OH molar ratio less than a certain value, slightly fluoridated hydroxyapatites will be formed (x .0.15), and above that ratio nearly pure fluor-apatite will be formed. Usually the F/OH ratio varies so that intimate mixtures of hydroxyapatite and fluorapatite will result (64). The effect of fluoride on teeth and bones are discussed elsewhere (52, 57). 

The effect of fluoridation with hydrofluoric acid on the. surface acidity of catalytic alumina was also studied by Ballou e< al. (340), About 1 % of fluoride was taken up by the catalyst. The surface acidity was estimated using a titration technique developed by Benesi (341a). After addition of varying amounts of butylamine in benzene solution, the color changes... 

Holland RI. Effect of fluoride on glycerol production in rat adipoc5des in vitro. Acta Pharmacol Toxicol (Copenh) 1977 41(2) 97-102. 

Table 6.1 Effect of fluoride on activity and stereoselectivity in the Ir-catalyzed addition of aniline to norbornene (Equation 6.5). ...

NaF was not mutagenic in bacterial assays. Although fluoride has been shown to be clas-togenic in a variety of cell types, the mechanism of clastogenicity has been attributed to the effect of fluoride on the synthesis of proteins involved in DNA synthesis and/or repair, rather than direct interaction between fluoride and DNA. In general, there was no effect on sperm morphology or the frequency of chromosomal aberrations, micronuclei, sister chromatid exchange, or DNA strand breaks in rodents treated in vivo. ... 

The effect of fluoride ions on the electrochemical behaviour of a metal zirconium electrode was studied by Pihlar and Cencic in order to develop a sensor for the determination of zirconium ion. Because elemental zirconium is always covered by an oxide layer, the anodic characteristics of a Zr/Zr02 electrode are closely related to the composition of the electrolyte in contact with it. These authors found the fluoride concentration and anodic current density to be proportional in hydrochloric and perchloric acid solutions only. In other electrolytes, the fluoride ion-induced dissolution of elemental zirconium led to an increase in the ZrOj film thickness and hindered mass transport of fluoride through the oxide layer as a result. The... 

Effect of fluoride-containing substrates on bone cells... 

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