Add to ORKGOur knowledge concerning the distribution of fluorine in drinking waters and the effect of such waters on the structure of the teeth has been appreciably expanded by the recent researches of Smith, Lantz, and Smith (1), Churchill (2), McKay (3), Kehr (4), Ostrem, Nelson, Greenwood, and Wilhelm (5), Boissevain (6), Dean (7), Sebrell, Dean, Elvove, and Breaux (8) and Boruff and Abbott (9). Smith, Lantz, and Smith (1), of the University of Arizona, were the first to show that mottled enamel is clue to fluorides in the drinking water; in fact, their analyses of waters from endemic areas show that the fluorine concentration in such waters is high