Studies with ingested fluoride have shown that part-time exposure to fluoridated drinking water at school (3 or 5 ppm F) may be effective against dental caries. Using this means of fluoridation or tablets as well, the postdevelopmental preeruptive and posteruptive effect of fluoride tablets was found to be important whereas prenatal fluoride did not provide a significant protection to either the deciduous or permanent dentition of the offspring. The well-known cariostatic effect of topical application has been confirmed in most of the recent studies, with 2 applications per year appearing to be necessary in order to reach a 20- to 40-percent inhibition. The value of the prophylactic pastes as a means of fluoridation is questionable.