The 10 pivotal caries clinical studies employed in a recent meta-analysis to compare the anticaries efficacy of sodium fluoride (NaF) and sodium monofluorophosphate (MFP) dentifrices were subjected to a critical review. When reporting the meta-analysis, the author (Johnson) considered these 10 pivotal caries clinical studies as "head-to-head" comparisons of NaF and MFP dentifrices. For the most part, it is difficult to find any common denominator among these 10 caries clinical studies since there were so many diverse factors associated with them. The 10 pivotal studies were conducted over a 20-year period of time in many different geographic areas of the world, using different protocols and study designs, different clinical examiners and caries assessment criteria, as well as evaluating commercially outdated or specially formulated dentifrices. Any attempt to integrate the results from these 10 studies is further complicated by the diversity of statistical methodology used to evaluate the results obtained from the studies. Also, in two of the 10 studies, the comparison of the fluoride dentifrices was obscured by the fact that the participating children used a fluoride mouthrinse during the course of the study. In any case, when all relevant dentifrice comparisons are made, the results of a critical review of the 10 pivotal ("head-to-head") caries clinical studies indicate the following: (1) In three of the studies (Gerdin/Zacherl/Forsman), depending upon how the data is viewed, it can either be shown that NaF dentifrices are favored over MFP dentifrices or that MFP dentifrices are favored over NaF dentifrices. (2) In one of the studies (Edward & Torell), the results are published only in abstract form and a full report of the study is not available. (3) In one of the studies (Koch, Petersson, Kling & Kling) it is reported that MFP dentifrices are favored over NaF dentifrices. (4) In two of the studies (Edlund & Koch, Koch et al) it is reported that NaF dentifrices are favored over MFP dentifrices. However, in both of these studies, there were serious imbalances in baseline caries status favoring the NaF dentifrice groups over the MFP dentifrice groups. In other words, the children using the MFP dentifrices were more prone to caries formation during the course of these studies than the children using the NaF dentifrices. Further, in these two studies there is a serious question regarding the soluble fluoride level of the commercially available MFP dentifrice that was used.(ABSTRACT TRUNCATED AT 400 WORDS)