Enamel Fluoride Uptake Affected by Site of Application: Comparing Sodium and Amine Fluorides

Abstract

In enamel fluoride uptake studies, the most frequently sampled site is the middle third of the buccal surface. Because different parts of the enamel surface vary in fluoride concentration, the present study investigated fluoride uptake at contrasting sites using two different topical agents. One was a neutral aqueous solution of sodium fluoride containing 2% w/w of fluoride, and the second was an aqueous solution of two amine fluorides containing 1% w/w of fluoride. The enamel of 10 pairs of clinically sound extracted human premolars was etched initially and after treatment with one of these agents on the cervical and middle thirds of the buccal surface and on the proximal surface, yielding the pre- and post-treatment fluoride concentrations of these sites at depths of 5 and 10 μm from the surface. Enamel treated with the amine F solution had significantly higher fluoride uptakes at all sites compared to the NaF-treated specimens. The differences in uptake from the two agents varied with site, being smallest for the buccal middle third enamel and greatest for the proximal enamel. It is suggested that these results relate to possibje differences in enamel maturation or to the presence of initial proximal caries, and the greater affinity of amine fluoride for porous enamel. The findings emphasise the importance of obtaining site-specific data in the study of fluoride in enamel.

Anticaries Potential of Commercial Dentifrices as Determined by Fluoridation and Remineralization Efficiency

“…The results of some in situ studies, in which u demineralized enamel samples were worn by volunteers, also showed fluoride uptake was less from NaMFP-containing toothpastes than from NaF-or AmF-containing toothpastes. 27,37 The most effective Group tested in this study (Fluocaril ® Bi-Fluoré 250) contained a combination of NaF and SMFP and a total F level of 2500 ppm F. This particular combination of fluoride actives coupled with a compatible silica based abrasive system provides a high level of fluoridating efficiency.…”

“…Biological availability of fluoride is highly dependent on the overall makeup of the toothpaste with certain ingredients and conditions being capable of reducing or at least minimizing potential anticaries performance. 24,[27][28][29][30][31][32] Other studies have utilized surface microhardness, or combinations of fluoride uptake and microhardness, as a means to demonstrate not only how much fluoride incorporates into a tooth during treatment but also to reflect mineral changes (remineralization) that have occurred within the tooth as a function of treatments. 15,16,23,33 Almost all of these studies compared products containing single sources of fluoride.…”