Caries prevention--fluoride.
A clear understanding of the mechanism of action of fluoride and its pharmacokinetics would ensure appropriate clinical use of fluoride and fluoride-containing modalities. Convincing evidence exists that fluoride has a major effect on the demineralization and remineralization of dental hard tissues, and that it interferes with the acid production from "cariogenic" bacteria. However, it has also been shown to be physiologically harmful if fluoride concentrations and/or exposure periods are inappropriate. In order to establish appropriate clinical concentrations and exposure periods for fluoride administration, this review is concentrated on the theme that fluoride controls but does not prevent caries. The review is organized along classical lines, with a discussion of the role of systemic vs. topical fluoride. Discussion of the systemic effects of fluoride includes ingestion through water fluoridation, fluoride supplements, topical fluoride applications, and dentifrices. The benefits and problems associated with the systemic route of fluoride administration are discussed with special reference to caries control and fluoride's mechanism of action and its toxic effect. The same discussions are focused on the role of the topical effects of fluoride, with particular emphasis placed upon: low vs. high fluoride concentrations; calcium fluoride vs. fluorhydroxyapatite; and fluoride distribution, in both the mouth and in the teeth.