Abstract
Previous studies have shown that children born and reared in a New Jersey area in which the drinking water contains 1.3 to 2.2 ppm. of natural fluoride are less subject to dental caries than children who have entered this area later in life, but there is also a familial factor involved. Examinations have been made to determine whether or not all teeth were protected to an equal extent. 874 life time residents and 725 migrants were compared with 6,000 children in Hagers-town, Md., where the water contains no fluoride. The teeth posterior in the mouth were less protected than those anterior. .