Statistical considerations related to a meta-analytic evaluation of published caries clinical studies comparing the anticaries efficacy of dentifrices containing sodium fluoride and sodium monofluorophosphate.

The comparison of the anticaries efficacy of dentifrices containing sodium fluoride (NaF) and sodium monofluorophosphate (SMFP) has recently been addressed through a meta-analysis of published head-to-head clinical trials. Such an analysis is used to provide an omnibus conclusion on the basis of summary information obtained from several individual studies. An important aspect of a meta-analysis is the determination of which studies from among those available in the relevant literature are to be incorporated into the calculations. The statistical literature provides several perspectives with respect to this issue. A recently-published meta-analysis by Johnson (1993) resulted in the conclusion that dentifrices containing NaF provide significantly lower caries increments than do those containing SMFP. However, a similar analysis utilizing studies identified by Volpe, Petrone & Davies (1993) suggests that no such significant difference exists. The resolution of such conflicting results rests on clinical judgment concerning the issue of study inclusion. The clinical significance of the results of both of these analyses was considered. Despite the differences in the analyses, both support the conclusion that dentifrices containing SMFP provide equivalent anticaries protection as do those containing NaF, in accordance with the standards established in the current American Dental Association Guidelines for the comparison of fluoride dentifrices.