The fluoride ion is, by far, the best known "tool" in the prevention of dental caries. It is widely used throughout the world. It has a systemic effect on developing teeth as well as a local topical effect on the enamel surface of erupted teeth. It can be used on an individual basis on high risk patients, as well as for mass prophylaxis on a population basis.This WHO report briefly summarizes scientific and clinical data on the safety and effectiveness of fluoride in the prevention of dental caries. Adopting a public health approach, the report aims to determine which of the currently available methods of fluoride administration will provide the best, safest, and most cost effective protection in different parts of the world, with different resources and population needs. Attention is given to the question of whether population-wide protection can be achieved without the development of dental fluorosis. All other potential risks linked to fluoride use are also briefly assessed in an effort to provide a solid public health service.The information is presented in 12 chapters. The first five concentrate on recent studies of fluoride that strengthen public health policy. Separate sections summarize what is known about environmental sources of fluoride, its metabolism and excretion, and its effect on teeth and bones. The second half of the report reviews clinical experiences with each of the main methods of fluoride administration, including fluoride in drinking water, fluoridated salt, fluoridated milk, fluoride supplements in the form of tablets and drops, fluoridated toothpaste, and topical use of fluoride. Each method is considered in terms of its safety, limitations, public health impact, cost, optimum concentration or dosage, and advantages in particular populations or situations. The report concludes with a discussion of problems caused by multiple sources of fluoride, followed by a series of 16 recommendations pertinent to public health policy and future research needs.This report gives a brief but very clear and correct overview of the present knowledge concerning the effect of fluoride in the prevention of caries, and every chapter is summarized in easily understood conclusions. However, nothing is mentioned about the mechanism of how the fluoride ion interacts with tooth structures and oral microflora. The report states that there is clear evidence that regular low-level exposure to fluoride can reduce the prevalence of caries, but a chapter explaining and comparing the different mechanisms behind a) systemic and topical use, and b) high dosage use on an individual basis and low dosage use on a population basis would have been very beneficial. Finally, fluorides and dental health would have been a more appropriate name.In conclusion, this report is a valuable, easily understood reference for the use of fluorides in the prevention of caries and a good addition to the library of nondental professional public health workers.