Abstract
In the community surveyed, the water supply was changed 19 yrs. ago from one containing no fluorine to one containing 1.4-2.2 p.p.m. fluorine. Thus the children had always used fluoride containing water whereas the parents had used such water for a shorter period of their life, the fluoride being absent particularly during early childhood. The data, while admittedly insufficient, indicate that a familial factor is involved since children whose parents show low incidence of dental disease also showed a low incidence while those children with one or both parents with a high incidence of dental disease were not so well protected.