Although dentifrices (in a modern sense) were first introduced at the turn of the century, it was not until the advent of fluoride-containing compounds that any of therapeutic value was produced. In the early post-war years, formulation compatibility difficulties occurred, with the result that none was demonstrated to have clinically proven efficacy until stannous fluoride was successfully incorporated in the "Crest" formulation of 1955. Thereafter, sodium monofluorophosphate (SMFP) appeared, to be followed by organic and acid-phosphate fluoride preparations, most of which were shown to produce clinical benefit over placebo controls. Since the late 1970's, however, such studies have been deemed unethical in many countries in view of the almost universal availability of efficacious fluoride dentifrices. While an NaF formulation was the first to be tested (albeit unsuccessfully) by Bibby (1945), there was a considerable time period before the arrival of both stable and effective silica-based systems in the early 1980's. Results of studies have varied, but the largest ever double-blind NaF/SMFP head-to-head dentifrice trial yet published (Stephen et al., 1994) has indicated a 6.4% significant benefit in favor of NaF (in silica) over SMFP. With respect to the effect of dentifrice fluoride levels, above 1000 ppm dose-response caries reductions have been obtained, but the efficacy of preparations containing 500 ppm F or less has yet to be demonstrated. In relation to root caries, Jensen and Kohout (1988) reported a 41.4% DFS significant reduction in subjects who used a NaF/silica dentifrice at 1100 ppm F, over a one-year period.