In a previous article (1) we analyzed a series of eight studies concerned with the effect of Duraphat in the prevention of dental caries by means of meta-analysis. A random effects model was used to estimate an overall effect size of caries reduction R and the corresponding confidence interval. In the present short communication we complement this previous study by neglecting the within study variation to the overall variation which is dominated by between study variation. This allows us to include a larger number of studies and thus make fuller use of the available information. We estimate nonparametrical confidence intervals for effect sizes (caries reduction) by means of the "bootstrap method". The overall caries reduction R on permanent teeth (14 studies) was estimated to be: R = 0.38 (95%-CI: 0.25-0.50).