Fluoride gel effective at reducing caries in children

DATA SOURCES: Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline , Embase, CINAHL, LILACS, ProQuest Dissertations and Theses, the Web of Science Conference Proceedings, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform.

STUDY SELECTION: Randomised or quasi-randomised controlled trials comparing topically applied fluoride gel with placebo or no treatment in children up to 16 years were considered. Studies had to be at least one year in duration with a frequency of application of at least once a year with blind outcome assessment. The main outcome was caries increment measured by the change in decayed, missing and filled tooth surfaces in both permanent and primary teeth (D(M)FS and d(e/m)fs).

DATA EXTRACTION AND SYNTHESIS: At least two reviewers extracted data and assessed risk of bias. The primary measure of effect was the prevented fraction (PF). Where data could be pooled random-effects meta-analyses were conducted. Potential sources of heterogeneity were examined in random-effects meta-regression analyses.

RESULTS: Twenty-eight trials involving 9140 children and adolescents were included. Most of the studies (20) were at high risk of bias, with eight at unclear risk of bias. Twenty-five trials (8479 participants) provided data for meta-analysis on permanent teeth, with a D(M)FS pooled prevented fraction (PF) estimate of 28% (95% CI; 19-36%; P < 0.0001; with substantial heterogeneity (P < 0.0001; I(2) = 82%); moderate quality evidence). Subgroup and metaregression analyses suggested no significant association between estimates of D(M)FS prevented fractions and the prespecified trial characteristics. However, the effect of fluoride gel varied according to the type of control group used, with D(M)FS PF on average being 17% (95% CI 3% to 31%; P = 0.018) higher in non-placebo-controlled trials (the reduction in caries was 38% (95% CI 24% to 52%; P < 0.0001, 2808 participants) for the ten trials with no treatment as control group, and 21% (95% CI 15% to 28%; P < 0.0001, 5671 participants) for the 15 placebo-controlled trials.A funnel plot of the 25 trials in the D(M)FS PF meta-analysis indicated a relationship between prevented fraction and study precision, with an apparent lack of small studies with statistically significant large effects.For primary teeth the d(e/m)fs pooled prevented fraction estimate for the three trials (1254 participants) = 20% (95%CI; 1% - 38%; P = 0.04; with no heterogeneity (P = 0.54; I(2) = 0%); low quality evidence).There was limited reporting of adverse events. Only two trials reported information on acute toxicity signs and symptoms during the application of the gel (risk difference 0.01, 95% CI -0.01 to 0.02; P = 0.36; with no heterogeneity (P = 36; I(2) = 0%); 490 participants; very low quality evidence). None of the trials reported information on tooth staining, mucosal irritation or allergic reaction.

CONCLUSIONS: The conclusions of this updated review remain the same as those when it was first published. There is moderate quality evidence of a large caries-inhibiting effect of fluoride gel in the permanent dentition. Information concerning the caries-preventive effect of fluoride gel on the primary dentition, which also shows a large effect, is based on low quality evidence from only three placebo-controlled trials. There is little information on adverse effects or on acceptability of treatment. Future trials should include assessment of potential adverse effects.