Fluoride uptake by enamel from stannous fluoride and prophylaxis pastes

Abstract

The purposes of this study were twofold: (1) to determine whether applying zirconium silicate prophylaxis paste (containing nine per cent stannous fluoride) prior to topical application of 10 per cent aqueous solution of stannous fluoride would promote a significantly greater enamel fluoride uptake than when the solution was applied alone; and (2) to determine whether rinsing the mouth with tap water immediately after these procedures would significantly affect enamel fluoride uptake. A modification of an in vivo, acid-etched enamel biopsy technique was used to measure fluoride and calcium contents of the outermost layer of enamel in first permanent molars and primary cuspids of 89 children. Four sites were biopsied prior to treatment. Treatments involved prophylaxes with a zirconium silicate paste either containing or not containing nine per cent stannous fluoride, followed by either a four-minute topical application of 10 per cent stannous fluoride in an aqueous solution or no such topical application. Some participants were instructed not to rinse for one-half hour; others were immediately offered unlimited quantities of tap water. Four other sites were biopsied one week after treatment; four more were biopsied two weeks after treatment. Pre- versus post-treatment differences were measured via a fluoride-sensitive electrode and atomic absorption spectrophotometry. Results were inconclusive. Enamel fluoride uptakes for most treatment groups appeared to be negative. Due to this seeming disagreement with the findings of many other investigators, and due to the very small numbers within treatment groups and biopsy sites, it was felt that uptake comparisons from group to group would be misleading. Tentative explanations for the unexpected results were offered.