Wafa Kashbour, Puneet Gupta, Helen V Worthington, Dwayne Boyers
Why is this question important?
Tooth decay (also called a cavity or caries) is when a small hole develops in a tooth. This happens because bacteria (tiny living organisms) that live in the mouth feed on sugar in the food we eat. As they feed, the bacteria produce acid that attacks teeth. If teeth are not cleaned regularly after eating, or if someone consumes a lot of sugary foods and drinks, the repeated acid attacks can create holes in the hard outer surface of the teeth (enamel). If untreated, these holes can deepen and damage the layer of tooth underneath the surface (dentine).
Many people around the world develop tooth decay at some point in their life. In most adolescents and children over the age of six years, decay damages the biting surfaces of the permanent teeth at the back of the mouth.
To prevent decay, dentists can apply a dental sealant, or a fluoride varnish, directly onto the back teeth. A dental sealant is a coating made from an adhesive material such as resin or glass ionomer, which the dentists applies once to teeth. It seals off the grooves in teeth that tend to collect food, and protects them from the acid. By comparison, a fluoride varnish is a sticky paste that contains high levels of fluoride; fluoride is a mineral naturally present in teeth that protects them from damage. Fluoride varnishes need to be applied to teeth by the dentist two to four times a year.
We reviewed the evidence from research studies to find out whether sealants or fluoride varnishes, or a combination, are better for preventing decay in the permanent back teeth of children and adolescents.
How did we identify and evaluate the evidence?
We searched the medical literature for randomised controlled studies (clinical studies where people are randomly put into one of two or more treatment groups), because these studies provide the most robust evidence about the effects of a treatment. We then compared the results, and summarised the evidence from all the studies. We assessed how certain the evidence was. To do this, we considered factors such as the way studies were conducted, study sizes and consistency of findings across studies. Based on our assessments, we categorised the evidence as being of very low, low, moderate or high certainty.
What did we find?
We found 11 studies that included 3374 children aged between five and 10 years at the start of the studies. Children were randomly assigned to treatment with either sealant or fluoride varnish, or both. They were followed for between one and nine years. Studies compared the number of children who had tooth decay in the dentine of their back teeth in different treatment groups.
The evidence was of very low certainty so we are not able to be confident in the findings.
When we combined four studies that compared resin sealants versus fluoride varnish, we found that neither intervention worked better than the other.
The three individual studies that compared sealants made from glass ionomer versus fluoride varnish could not be combined and had mixed results.
One small study found that using both sealants and fluoride varnish may work better than using fluoride varnish alone.
Five studies reported that no side effects were associated with the use of either sealants or fluoride varnishes. The other studies did not mention whether or not any side effects occurred.
What do these results mean?
At present, we do not know whether it is better to apply sealants or fluoride varnish to prevent tooth decay in children's back teeth. We do know that both interventions are effective for reducing tooth decay, and current evidence does not suggest that one works better than the other.
Fourteen studies are currently underway. Their findings could improve the evidence in future versions of this review.
How‐up‐to date is this review?
The evidence is current to March 2020.
Kashbour W, Gupta P, Worthington HV, Boyers D. Pit and fissure sealants versus fluoride varnishes for preventing dental decay in the permanent teeth of children and adolescents. Cochrane Database of Systematic Reviews 2020, Issue 11. Art. No.: CD003067. DOI: 10.1002/14651858.CD003067.pub5.