The Reaction of Monofluorophosphate with Apatite

Abstract

The action of sodium monofluorophosphate on Syntheti chydroxyapatites has been studied using pure mono- syntheticfluorophosphate solutions.Monofluorophosphate-treated hydroxyapatite was less soluble in acid buffer than fluoride-treated mineral of similar fluorine content. During the reaction some orthophosphate was liberated from the solid and addition of orthophosphate to the monofluorophosphate inhibited subsequent uptake of fluorine by the hydroxyapatite. The FPO₃ anion was present in the treated hydroxyapatite and was shown to have replaced the hydrogen phosphate group of the calcium-deficient hydroxyapatites. In this way the capacity of a calcium-deficient hydroxyapatite for uptake of monofluorophosphate was related to its HPO₄ content; i.e. its Ca:P molar ratio. Replacement of the acid phosphate groups of the hydroxyapatite, either by FPO₃ substitution or by thermal condensation to pyrophosphate reduced the isotopic exchange of orthophosphate by the mineral.

Fluoride in Plaque Fluid, Plaque, and Saliva Measured for 2 hours after a Sodium Fluoride Monofluorophosphate Rinse

“…However, reviews of the clinical literature comparing the anticaries efficacy of dentifrices containing these ingredients have varied from those that suggest clinically equivalent effects [Proskin, 1993;Volpe et al, 1993;Mellberg, 1991] to those which suggest that a small advantage is provided by NaF [Johnson, 1993;Stookey et al, 1993]. Among the mechanistic reasons that have been postulated to explain these apparently discrepant results are (1) a specific effect of the MFP ion to reduce enamel solubility [Grönetal et al, 1971;Ingram, 1972;Duff, 1983], and (2) a synergistic effect of the MFP ion with calcium and phosphate. With regard to the first mechanism, the persistent concentration of the MFP ion found in the fluid phase of plaque and saliva ( fig.…”

Enhanced Uptake of Monofluorophosphate by Hydroxyapatite (Short Communication)

“…This probably includes adsorption onto the tooth surface initially, although there is no simple correlation between total fluoride uptake and caries reduction [Aasenden et al, 1972;Mellberg and Ripa, 1983;Retief et al, 1987], It is useful to deter mine how various parameters can influence the up take of fluorides into dental enamel. Uptake of MFP by hydroxyapatite (FlAp) has been studied previously by a number of investigators under varying condi tions [Ericsson, 1963;Ingram, 1968;Gron etal., 1971;Ingram, 1972;1973;Eanes, 1976;Benton et al, 1980]. Recently, soluble ionic calcium was shown to increase the uptake of fluoride by etched and white spot bo vine enamel from MFP solutions and dentifrice slur ries [Mellberg and Chomicki, 1982], From this study it was apparent that certain metal ions may increase MFP uptake by HAp.…”

The effect of monofluorophosphate implant in white rat mothers towards the level of fluor in the incisors of their young babies (Rattus-rattus)

“…9 Thus, if the reason of the use of MFP is because of anti-caries activities in MFP with its toxicity about one third lower than that in NaF, 3 it still can be degraded by alkali or acid phosphate through hydrolysis process, 5 and by the substitution of the structure of phosphate hydrogen on hydroxy apatite with monofluorophosphate ion. 6 The average of fluoride contained on the incisors of those thirty-five day old white rat babies and the binding of fluoride ion on the teeth, actually depends on the level of fluoride in their blood plasma. The increasing of fluoride level in the certain availability of plasma will increase the amount of fluoride bound on teeth.…”

“…3 MFP is chosen because it has anti-caries, its toxicity about one third lower than that in NaF, 4 it still can be degraded by alkali or acid phosphate through hydrolysis process, 5 and by the substitution of the structure of phosphate hydrogen on hydroxy apatite with monofluorophosphate ion. 6 The dissolution of MFP will 20 times faster if the level of calcium ions is so high to make calcium-monofluorophosphate compound that easily dissolved. 7 In recent years, various products of medicines modified with controlled fluoride release have actually been developed for several reasons.…”