AbstractThe effect on caries prevalence of the permanent dentition was evaluated alter 5 years of weekly rinsing (139 scheduled rinses') with a 0.2% neutral NaF solution. The program was conducted in the Three Village Central School District. New York, U.S.A. (F≤0.1 part/106). First to sixth grade children who rinsed From 1 to 5 years respectively had a caries prevalence reduction of 45.3% (DMFT) and 47.4% (DMFS) compared to baseline scores of children who were examined be lore the rinsing program began. The highest caries reduction, 81.3%, was found on proximal surfaces. Two variables influenced the cariostatic benefits associated with fluoride rinsing. The younger that children entered the program and the longer that they rinsed, the greater were the accumulated benefit