A comparison of the anticaries effectiveness of daily and weekly rinsing with sodium fluoride solutions: findings after two years.

In 1976, a three-year study was started in Biddeford, Maine, a non-F city, to compare the cariostatic effect of weekly use of a 0.2~ NaF rinse with daily use of a 0.05~ NaF rinse in a public health program. Participants in grades 5-7 (ages 10-12) in public and parochial schools were randomly assigned to the weekly F rinse, daily F rinse or control group that rinsed weekly with a placebo solution (0.1 ~ NaC1). Findings reported after two years showed anticaries effects for both F rinse regimens, but no statistically siguificant difference between them. Year one to year two increments showed that subjects in the weekly and daily F rinse groups had 1.61 and 1.18 mean DMFS compared with 2.01 DMFS for children in the control group or 19.9~ and 41.3~g fewer new carious surfaces, respectively. Although the difference between the daily and weekly rinses was not sta tistically significan t, the possibility of a type H error (to falsely conclude no difference between the treatments) in this experiment is large. It should be noted that findings of this study pertain to the use of tluoride mouthrinses in a public health program and should not be generalized to