Commentary

Dental caries remains a significant public health problem, with untreated caries in permanent teeth being the most prevalent condition noted in the 2010 Global Burden of Disease study.1 Around 35% of the global population, or 2.4 billion people, are affected, with the World Health Organisation estimating that it is the fourth most expensive chronic disease to treat.2 Consequently, the prevention of caries in children and adolescents is considered a priority for dental services. Topical fluoride is available in a number of formats eg toothpastes (dentifrices), mouthrinses, gels and varnishes and widely used in caries prevention programmes and widely recommended in evidence-based guidelines.3, 4

This current review is an update of the Cochrane review of fluoride gels for preventing caries in children and adolescents that was first published in 2002 and is one of a series of Cochrane reviews on topical fluoride interventions.5, 6, 7, 8, 9, 10, 11, 12, 13, 14

The review has been conducted using the usual robust Cochrane methodology and it is worth noting that one of the inclusion criteria is that studies were required to have used blind outcome assessment. This update adds just three new trials to the review; a majority (12) were conducted in the 1960s, seven in the 1970s, five in the 1980s, one in the 1990s with another three trials conducted in the late 1990s and early 2000s. A range of fluoride concentrations (2425 ppm F to 12,500 ppm F) were used in the studies with application being carried out by professionals (operator applied) in seventeen studies.

Overall the review demonstrates an average 28% reduction in decayed missing and filled surfaces in the permanent teeth with the confidence interval suggesting that the true effect could lie somewhere between 19-36%. The authors highlight that a smaller reduction of 21% was seen in trials that used a placebo gel compared with those trials where the control group received no treatment, which demonstrated a 38% reduction. Fewer trials were conducted on primary teeth, with the available evidence suggesting a 20% reduction in decayed, missing and filled tooth surfaces. There was little information in the included studies on adverse effects. There was not sufficient information available to assess the impact of initial level of caries severity, background exposure to fluoride, mode of use frequency of use or fluoride concentration.

One potential concern about the findings is linked to the age of the included studies with many having been published prior to the widespread availability of fluoride toothpaste. In their discussion the review authors' note that the data from the three studies conducted in the Netherlands and published in the 2000s demonstrated similar effects to those of the overall pooled sample.

In conclusion, this review provides moderate quality evidence that fluoride gels provide a 28% reduction in decayed missing and filled teeth. While this represents an important level of caries reduction, these gels are typically applied in trays with application times varying from 2-10 minutes and anecdotally many patients find this unpleasant, (I certainly did when receiving fluoride gel treatment as a child), and nausea, vomiting, headache and abdominal pain have been reported. As a result there has been an increasing in use in fluoride varnish, which has been shown to have a larger caries reduction (43%) and is easier to apply.5