Abstract: We found no evidence comparing slow-release fluoride devices against other types of fluoride therapy. We found only one double-blind RCT involving 174 children comparing a slow-release fluoride device (glass beads with fluoride were attached to buccal surfaces of right maxillary first permanent molar teeth) against control (glass beads without fluoride were attached to buccal surfaces of right maxillary first permanent molar teeth). This study was assessed to be at high risk of bias. The study recruited children from seven schools in an area of deprivation that had low levels of fluoride in the water. The mean age at the beginning of the study was 8.8 years and at the termination was 10.9 years. DMFT in permanent teeth or dmft in primary teeth was greater than one at the start of the study and greater than one million colony-forming units of Streptococcus mutans per millilitre of saliva. Although 132 children were still included in the trial at the two-year completion point, examination and statistical analysis was performed on only the 63 children (31 in intervention group, 32 in control group) who had retained the beads (retention rate was 47.7% at 2 years). Among these 63 children, caries increment was reported to be statistically significantly lower in the intervention group than in the control group (DMFT: mean difference -0.72, 95% confidence interval (CI) -1.23 to -0.21; DMFS: mean difference -1.52, 95% CI -2.68 to -0.36 (very low-quality evidence)). Although this difference was clinically significant, it only holds true for those children who maintain the fluoride beads; over 50% of children did not retain the beads. Harms were not reported within the trial report. Evidence for other outcomes sought in this review (progression to of caries lesion, dental pain, healthcare utilisation data) were also not reported. There is insufficient evidence to determine the caries-inhibiting effect of slow-release fluoride glass beads. The body of evidence available is of very low quality and there is a potential overestimation of benefit to the average child. The applicability of the findings to the wider population is unclear; the study had included children from a deprived area that had low levels of fluoride in drinking water, and were considered at high risk of caries. In addition, the evidence was only obtained from children who still had the bead attached at 2 years (48% of all available children); children who had lost their slow-release fluoride devices earlier might not have benefited as much from the devices.

Plain-language summary: Authors from Cochrane Oral Health carried out this review of existing studies and the evidence is current up to 23 January 2018. We searched scientific databases for clinical trials in children or adults treated with slow-release fluoride devices compared with another type of fluoride treatment (e.g. toothpaste, mouthrinse, gel, or varnish), placebo (a pretend treatment), or no treatment (usual care). Treatments had to be used and monitored for a minimum of 1 year. We found one study that randomised 174 children to either slow-dissolving, fluoride-releasing glass beads or placebo beads. The setting was an inner city school in an area served with low-fluoride water. Only 48% of children retained the beads and were available for analysis. There is insufficient evidence to determine whether slow-release fluoride devices (such as glass beads) help reduce dental decay. Retention of the beads is a problem. The evidence relating caries increment, side effects and retention was considered to be very low quality.