Plaque Fluoride Concentrations Are Dependent on Plaque Calcium Concentrations

Abstract

Despite the 1,000-fold difference between the fluoride concentrations ([F]) in dentifrices and fluoridated drinking water, clinical and epidemiological studies have shown that they have similar cariostatic effects. This double-blind, crossover study was done to determine whether the [F] in dental plaque is related more to the [F] of the dentifrice used or to the plaque concentrations of calcium and magnesium. The subjects (n = 13) were adults and residents of a city served with fluoridated drinking water. After 1 week of using a fluoridated dentifrice (940 ppm) or a placebo dentifrice, whole saliva and plaque were collected 1.0 h and approximately 12 h after the last use of the dentifrices. The average salivary [F] after brushing with the F dentifrice was higher than after using the placebo. The average plaque [F] 1.0 h after brushing with the F dentifrice was higher than after using the placebo (p < 0.01), but the difference at 12 h was not significant. Plaque [Ca] and [F] were directly related under all experimental conditions (p = 0.0001). The relationships between plaque [Mg] and [F] were weaker and inconsistent. Based on these findings and reports in the literature it is concluded that, for persons whose drinking water is fluoridated, plaque [F] throughout much of the day is not significantly increased by the use of a fluoridated dentifrice. Instead they are directly related to plaque [Ca]. These findings offer at least a partial explanation for why fluoridated dentifrices and drinking water have similar cariostatic effects.

Artificial biofilm thickness and salivary flow effects on fluoride efficacy – A model development study

“…A potential solution was offered initially by Lecomte and Dawes [11], later adapted by Blake-Haskins, et al [12], who introduced the concept of 'artificial biofilms' by utilizing an agarose gel as a surrogate for dental biofilms. The importance of calcium for enhanced fluoride retention was demonstrated [12] which is in agreement with later in vivo studies on human biofilms [13] and on the role of calcium fluoride in caries prevention in general [14], thereby highlighting the potential value of this experimental approach.…”

Fluoride retention in saliva and in dental biofilm after different home-use fluoride treatments

“…30 The results of this study are in agreement with the findings of most of the studies conducted in areas with a fluoridated water supply. 13,20,21,22 These studies also did not show a long-term effect on the fluoride concentration in saliva and in dental biofilm compared to baseline values. A possible explanation for these is that plaque-binding sites for long-term fluoride retention are occupied by fluoride ions largely in communities with fluoridated water, but not where the water contains only traces of this ion.…”

“…15,16,17,18,19 Numerous studies have determined fluoride concentrations in saliva and in dental biofilm over long periods in areas with fluoridated water supply; however, they yielded contradictory results. 13,20,21,22,23,24 Since the literature remains inconclusive in regard to this aspect, the aim of this study was to determine the fluoride retention in saliva and in dental biofilm after different home-use fluoride treatments in volunteers living in an area with a fluoridated water supply.…”

Plaque Fluoride Concentrations in a Community without Water Fluoridation: Effects of Calcium and Use of a Fluoride or Placebo Dentifrice

“…A recent report [Whitford et al, 2002] described the results of a double-blind, crossover study designed to determine the fluoride concentrations in whole saliva and dental plaque following the use of two dentifrices, one of which contained fluoride (940 mg/kg fluoride as NaF) and a placebo which was identical to the fluoride dentifrice except that it contained no fluoride. The subjects were residents of Augusta, Ga., USA, which has had a controlled water fluoridation program (annual range 0.75-1.0 ppm) for over 40 years.…”