FLUORIDE UPTAKE IN ENAMEL - INVITRO COMPARISON OF TOPICAL AGENTS

The penetration profiles of F have been investigated using secondary ion mass spectrometry, at depths of ca. 0.1–1.5 μm in specimens of permanent and deciduous human enamel after application of different varnishes and toothpastes. The treatment with NaF containing varnishes was found to result in gains of more than 1,000 wt-ppm F even at 1.5 μm depth, roughly proportional to the root of the fluoride content in the agent. Silane varnish yields similarly high F uptake and a particularly flat penetration profile. While F from the NaF varnish in the main seems to enter the dental tissue, that from the silane to a large extent remains in the agent medium, penetrating the porosities of enamel. Some evidence is seen of a chemical transformation of superficial enamel in the presence of the silane agent. Acidulated NaF toothpastes yield considerably higher and flatter F penetration profiles than all neutral or basic toothpastes investigated.