Using the DMF gender difference to assess the "major" role of fluoride toothpastes in the caries decline in industrialized countries: a meta-analysis.

The regular use of fluoridated toothpastes has been ascribed a major role in the observed decline in caries prevalence in industrialized countries during the last 20 to 25 years, but only indirect evidence supports this claim. The purpose of this study was to test the hypothesis that the more frequent use of fluoride toothpastes by girls than by boys has reduced the relative age-specific D(M)FT gender difference, and that this difference should decrease with increasing age and fluoride toothpaste exposure among adolescents. The material comprised 8,777 subjects 12 to 17 years of age from the pre-fluoride toothpaste era (1946-1959) and 39,903 from the period when use of fluoride toothpaste had become common (1983-1993) in industrialized countries. Meta-analyses were done using the relative age-specific mean D(M)FT difference between girls and boys. Separate analyses were carried out for subgroups of studies/countries to check for confounding. Regardless of analytical approach, no evidence was found to support the hypothesis. It is concluded that the gender difference in fluoride exposure due to tooth brushing frequency is too small to matter, that the study lacked power, or that the role of fluoride toothpastes in the caries decline has been overrated.