There have been important developments regarding the effects of fluorine on dental caries which justify the optimistic view that dental caries may be partially controlled by some form of fluoride therapy. The direct fluorination of drinking waters of large communal centers is in process of study as a caries control measure and represents a unique and heretofore unutilized approach toward a mass preventive in medicine and dentistry. The first direct fluorination of community water was begun on Jan. 28, 1945, in Grand Rapids, Mich. Other cities now artificially providing 1.0 part per million of fluorine in their drinking water are, Newburgh, N. Y.; Brantford, Ontario, Canada; Midland, Mich.; Sheboygan and Madison, Wis.; Evanston, Ill., Ottawa, Kan., and Marshall, Texas. No foodstuff in the average American diet can compare with drinking water containing 1.0 part per million or more of fluorine as a source of fluorine in human nutrition, but it