The role of 'CaF2-like' material in topical fluoridation of enamel in situ.

In this paper the role and importance of 'CaF2-like' material deposited on enamel (Fon) by means of an APF gel and the varnishes Duraphat and Fluor Protector are described and discussed. The amount of Fon, determined by KOH extraction, is a measure of the amount of CaF2-like material on the enamel surface. Fluoride in the enamel (Fin), determined by etching, is the amount of F- bound in the solid enamel. Fon and Fin data are presented after various F- treatments and after wearing enamel slabs in dentures for a period of 1 week. The results of this work show that if we compare the three fluoridating agents, APF gel, Duraphat varnish, and Fluor Protector varnish in situ, only Fluor Protector shows a measurable amount of Fon after 1 week. The amounts of Fon acquired by the enamel surface (one application) rank as APF gel approximately Duraphat much less than Fluor Protector. Most likely, Fon in situ leaches away through the pellicle, with an apparent diffusion coefficient of about 10(-6) cm2.sec-1. The Fin data show that after APF gel or Duraphat treatment a substantial amount of Fin leaches away during 1 week in situ; the Fin values of Fluor Protector do not change. The efficiency of the fluoridating agents is most likely determined by the application period and fluoride availability. For APF gel, Duraphat, and Fluor Protector about 5%, 1%, and 44% of the available fluoride participates in the fluoridation process. CaF2-like globules are known to precipitate after gel or varnish treatment on the enamel surfaces and can be dissolved in KOH solution.(ABSTRACT TRUNCATED AT 250 WORDS)