Fluoride gel applications reduce caries incidence

Question: Do fluoride gels reduce dental caries? Objective: To determine the effectiveness and safety of fluoride gels in the prevention of dental caries in children and to determine the relationship to initial caries severity, background exposure to fluoride, and the mode and frequency of gel use. Data Sources: The purpose was to identify all relevant studies from 1965. Electronic searching of the MEDLINE, EMBASE, SCISEARCH, SSCISEARCH, ISTP, BIOSIS, CINAHL, ERIC, Dissertation Abstracts, LILACS/BBO databases and of the Cochrane Controlled Trial and Medline registers has been attempted. Furthermore, all eligible trials, meta-analyses and review articles were scanned for relevant references. In addition 7 journals were hand searched and personal contact with authors and manufacturers was achieved while searching for unpublished data. Study Selection: Exclusively RCTs and quasi-RCTs with blind outcome assessments, comparing groups applying fluoride gel with placebo or no treatment groups consisted of children up to 16 years old at baseline were included in this review. Studies were excluded where the participants were selected on the basis of special health conditions, were carrying orthodontic bands (or other appliances), and/or used additional caries preventive agents (eg chlorhexidine or sealants etc.), as well as studies that provided results only on plaque/gingivitis, calculus, dentin hypersensitivity or physiological fluoride. Data Extraction and Synthesis: The first reviewer assessed the quality of all included studies. The second reviewer duplicated the process for a random sample of ≈1/3 of them. In addition, the 2nd reviewer independently assessed any study that could not be classified by the first. A third reviewer was consulted to resolve any disagreement. Attempts were made to contact authors of trials that could not be classified in order to ascertain whether the inclusion criteria were met. Agreement was good for allocation (kappa=0.61) and blinding (kappa=0.73). There was a considerable difference in the quality of the 25 studies in this review. Random effects meta-analyses were performed where data could be pooled. Potential sources of heterogeneity were examined in random effects meta-regression analyses. Results: Twenty-five studies were included, involving 7747 children. For all the 23 trials, that contributed data for meta-analyses, combined the DMFS pooled prevented fraction estimate was 0.28, suggesting a substantial benefit from the use of fluoride gel. Statistically significant heterogeneity was observed (p<0.0001). Uni-variate meta regression analysis suggested no significant association between estimates of DMFS prevented fractions and length of follow-up, allocation concealment, blinding of outcome assessment or drop out rate. Populations with a caries incidence of 2.2 DMFS/year had an NNT=2 (95% CI=1 to 3). For populations with a caries incidence of 0.2 DMFS/yr had an NNT=24 (95% CI=18 to 36). A funnel plot suggests a balancing asymmetry with a single large study demonstrating the largest positive effect and a single small study demonstrating a large deleterious effect. Only two studies reported on adverse effects (nausea/vomiting). Conclusions: This review suggests that the application of fluoride gels, either professionally or self-applied, is associated with a substantial reduction in caries increment. This effect was independent of other fluoride sources, but did depend on application frequency. Given the large beneficial effect, further demonstration of efficacy is not needed. However, it is important that future trials examine potential adverse effects as well as application frequency.