In vivo Effect of a Fluoridating Varnish with Various Fluoride Contents on Human Enamel

The purpose of this in vivo study was to compare the fluoride acquisition on (Fon) as well as in (Fin) enamel after a single application of polyurethane varnishes. The varnishes investigated were all on the same polyurethane basis but contained either 0, 0.05, 0.1 or 0.7 wt% fluoride. The varnishes were removed after an application period of 24 h. A new technique for in vivo experimentations was developed using frame prostheses with slots to hold the experimental human enamel specimens. 11 participants carried 52 enamel specimens in frames for 1 week. Fon and Fin measurements were done after the experiment. The acquired amount of fluoride as Fon after 1 week was such that varnish 0.7% > varnish 0.1% ≃ varnish 0.05% ≃ varnish 0% ≃ control. The acquired fluoride as Fin showed the same ranking. From a clinical point of view this study shows that it is not interesting to consider varnishes with a content of 0.1 wt% F–– or lower for caries prevention, because 6 days after removal both Fon and Fin are hardly different from unfluoridated conditions