There is current evidence of a new interest in the extent to which tissue tolerates fluoride and in the potential benefits of ingested fluoride in the management of various general illnesses, notably metabolic bone diseases. The fluoride dosages tolerated in tissue culture (5 to 10 parts of fluoride ion per million) and used in recent medical applications (20 to 100 mg of fluoride ion per d,ay) suggest that ingestion of water containing fluoride at a concentration of 1 part per million (0.5 to 1 mg of fluoride ion per day), as recommended for the prevention of dental caries, provides a higher margin of systemic safety than is generally believed.This contrast between potential medical and conventional dental applications of fluorides struck me as particularly significant when I recently served as a U.S. representative before a World Health Organization conference in Geneva, Switzerland. Here representatives from many countries were convened to consider the worldwide incidence of dental disease, with particular reference to the need for and potential impact of expanded dental research. A paradox appeared in observations indicating continued widespread concern about the presumed "poisoning" effects of supplementation of the fluoride content of drinking water to the level recommended for the prevention of dental caries and in data showing a worldwide spread of dental disease, both in the developing countries (in some of which there is only one dentist for each 1 million people) and in the affluent societies, where one dentist for each 1500 to 3000 people is the ratio considered necessary to meet the public demandthough not the total need-for dental treatment.The purpose of this article is to provide a summary of very recent ref-
