Tooth decay affects 60% to 90% of children. Levels of tooth decay vary between and within countries, but it is generally true that children in lower socioeconomic groups (measured by income, education and employment) have more tooth decay. Over time, untreated tooth decay causes progressive destruction of the tops of teeth (crowns); this is often accompanied by severe pain. Repairing and replacing decayed teeth is extremely costly in terms of time and money and is a major drain on the resources of healthcare systems. The prevention of tooth decay in children and adolescents is regarded as a priority for dental services and is considered more cost-effective than its treatment. The use of fluoride, a mineral that prevents tooth decay, is widespread. As well as occurring naturally, fluoride is added to the water supply in some areas, and it is used in most toothpastes and in other products that are available to varying degrees worldwide. As an extra preventive measure there are other ways of applying fluoride directly to teeth, such as mouthrinses, lozenges, varnishes and gels. Fluoride gel is usually applied by a dental professional, or self applied under supervision (depending on the age of the child), from once a year to several times a year. The gel is usually placed in a tray that the child or young person must keep in their mouth and bite into for about four minutes. It is not uncommon for young people to accidentally swallow some of the gel; feelings of sickness, vomiting, headache and stomach pain have been reported when too much is swallowed. Due to this risk of toxicity, fluoride gel treatment is not generally recommended for children younger than six years old.
What was the research?
A systematic review of the evidence to find out the effectiveness of fluoride gel for the prevention of tooth decay (dental caries) in children and adolescents compared to placebo (a treatment without the active ingredient fluoride) or no treatment. The team also considered the safety of fluoride gels.
Who conducted the research?
The research was conducted by a team led by Valeria C.C. Marinho from Barts and The London School of Medicine and Dentistry, Queen Mary University of London, on behalf of the Cochrane Oral Health Group. Helen V. Worthington, Tanya Walsh and Lee Yee Chong were also on the team.
What evidence was included in the review?
Data was extracted from 28 randomised controlled trials. Over 9,000 children under the age of 15 years participated in the trials, and were randomly assigned to treatment with fluoride gel or to a control group using placebo gel or receiving no treatment
What did the evidence say?
This review update confirmed that fluoride gel can reduce tooth decay in children and adolescents. We combined the results of 25 trials and found that on average there is a 28% reduction in decayed, missing and filled tooth surfaces (21% reduction in trials that used a placebo gel in the control group and 38% reduction in trials where the control group received no treatment) in permanent teeth. From the three trials looking at the effect of fluoride gel on first or baby teeth, the evidence suggests that using fluoride gel results in a 20% reduction in decayed, missing and filled tooth surfaces. We found little information about unwanted or harmful effects or how well children and young people were able to cope with the application of the gel.
How good was the evidence?
The evidence available for permanent teeth is of moderate quality. The evidence on baby teeth is low quality because of the small number of studies available. The evidence available for adverse effects is very low quality.
What are the implications for dentists and the general public?
This review suggests that the application of fluoride gels, either by professionals or self applied, is associated with a large reduction in caries increment in permanent teeth in children (the quality of evidence is moderate). We are less certain of the large reduction observed in the primary dentition (low quality evidence). Unfortunately, there was little information on the risk of adverse effects with this treatment. The evidence seems applicable to current clinical practice. For example, with regards to exposure to other fluoride sources in the population, although the evidence base for fluoride gel is mainly from older studies conducted when fluoridated toothpaste was not widely available, we have found no evidence of smaller treatment effects in the trials conducted more recently.
What should researchers look at in the future?
We have identified a large number of trials, but the quality of the trials included in this review is relatively poor, with many reports lacking important methodological details. This is likely to be due in part to the fact that most of the trials are relatively old. Many characteristics considered crucial for excluding bias, such as clearly stated randomisation and allocation concealment, have been emphasised more in recent years, after most of the gel trials were reported. Researchers should pay particular attention to reporting the methods of randomisation and the history and reasons for dropouts and exclusions throughout the course of the study. Nevertheless, given the clarity of the results for the permanent dentition (and general lack of recommendation for fluoride gel use in young children), further randomised comparisons of fluoride gel and placebo/no treatment alone would be hard to justify.
Marinho VCC, Worthington HV, Walsh T, Chong LY. Fluoride gels for preventing dental caries in children and adolescents. Cochrane Database of Systematic Reviews 2015, Issue 6. Art. No.: CD002280. DOI: 10.1002/14651858.CD002280.pub2.