Review of the Month: a coat of varnish?


c. Indian Health Service

Tooth decay or dental caries is a worldwide health problem, up to 90% of children are affected. Fluoride is a mineral which prevents tooth decay. It can be applied directly to children’s teeth in the form of a varnish, by a dental professional.  How effective is it as a prevention measure? Our Review of the Month for July is an update – hot off the press!

What was the research?

A systematic review of the evidence to find out how effective fluoride varnish is for prevention of tooth decay in children and adolescents. In all cases, the varnish was compared to a placebo, i.e. a treatment without fluoride.

Who conducted the research?

The research was conducted by a team led by Valeria Marinho from Barts and the London School of Medicine and Dentistry in the UK, on behalf of the Cochrane Oral Health Group. Helen Worthington, Tanya Walsh and Jan Clarkson were also on the team.

What evidence was included in the review?

Data was extracted from 22 randomised controlled trials. A total of 12,455 children participated in the trials, and were randomly assigned to treatment with fluoride varnish, or placebo.

What did the evidence say?

The evidence says that fluoride varnish can be used to prevent tooth decay. 13 of the trials looked at older children who have permanent (adult) teeth, and fluoride varnish was found to reduce decayed or missing teeth by 43%. Children who still have their baby or milk teeth were covered in 10 of the trials. For this group of children, fluoride varnish reduced decayed or missing teeth by 37%.

There was little information in the trials on whether fluoride varnish has significant side effects.

How good was the evidence?

The evidence is of moderate quality. None of the 22 included trials were assessed as having a low risk of bias. 68% of the trials were at high risk of bias. This is due to several factors, including the high drop out rate of the participants, and poor quality reporting.

What are the implications for dentists and the general public?

The review found that the application of fluoride varnish 2 to 4 times per years, either in permanent or baby teeth, can reduce tooth decay in children. This applies in populations with different levels of risk and exposure to other sources of fluoride (such as fluoride in the water supply).

What should researchers look at in the future?

Despite the large number of trials on fluoride varnish, there are not enough high quality studies at low risk of bias. Well designed studies are needed. Future studies should also look at the potential side effects of fluoride varnish (for example, allergic reactions) and should look at fluoride varnish used in combination with other preventative measures.


Marinho VCC, Worthington HV, Walsh T, Clarkson JE. Fluoride varnishes for preventing dental caries in children and adolescents. Cochrane Database of Systematic Reviews 2013, Issue 7. Art.No.: CD002279. DOI: 10.1002/14651858.CD002279.pub2.