Slowly does it: no evidence that slow-release fluoride devices are effective

Tooth decay is not distributed evenly among the population, with certain groups being at greater risk of developing tooth decay than others. For example, research in Scotland has shown that 50% of tooth decay occurs in 11% of 5-year-old children and only 6% of 14-year-old children. In light of this uneven distribution, it is often suggested that these small percentages of children may be offered targeted-caries preventive measures to great potential effect, in a cost effective manner. One such preventive measure is the use of slow-release fluoride devices (e.g. slow-dissolving fluoride-releasing glass beads).

What was the research?

A systematic review to assess the effects of different types of slow-release fluoride devices on preventing, stopping, or reversing the progression of tooth decay on all surface types of deciduous (‘baby’) and permanent teeth.

Who conducted the research?

The research was conducted by a team led by Lee-Yee Chong of the UK Cochrane Centre, on behalf of Cochrane Oral Health. Jan E. Clarkson, Lorna Dobbyn-Ross and Smriti Bhakta were also on the team.

What evidence was included in the review?

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 randomised controlled 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.

What did the evidence say?

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.

How good was the evidence?

The evidence relating to caries increment, side effects and retention was considered to be very low quality. We are uncertain that this intervention is effective.

What are the implications for dentists and the general public?

We conclude that there is only limited and very low-quality evidence that provides insufficient information to determine whether slow-release fluoride devices in the mouth may provide a measure of protection against dental disease progression. The quality of the evidence was very low because of a high proportion of children not included in the study’s final analysis and serious uncertainty applicability of study findings to the general practice. The generalisability of these findings to routine dental practice was questioned by the difficulties of retention of the devices by the study population (children at high risk of caries, living in an area with low levels of fluoride in tap water).

What should researchers look at in the future?

The study identified for this review did not provide reliable evidence to answer the main question of the review. Some limited evidence was found but weaknesses in this were evident. To remedy these weaknesses, much larger, well-conducted trials (randomised controlled trials, and where possible, double-blinded) should be carried out.

This review will not be updated unless and until more evidence is available.


Chong LYClarkson JEDobbyn-Ross LBhakta SSlow-release fluoride devices for the control of dental decayCochrane Database of Systematic Reviews 2018, Issue 3. Art. No.: CD005101. DOI: 10.1002/14651858.CD005101.pub4.

This post is an extended version of the review’s plain language summary, compiled by Anne Littlewood at the Cochrane Oral Health Editorial Base.


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