Randomised controlled trials (RCTs) or quasi-RCTs were selected if the assess application of topical fluoride varnish to primary dentition and incidence of caries in primary dentition. Trials of children aged six years or younger (regardless of caries experience at the start of the trial) were eligible for inclusion. The fluoride varnish could be given in any quantity, or concentration or at any application interval, on selected or unselected surfaces using any application technique. Trials that used a split-mouth design and intentionally administered other fluoride products in addition to varnish for the intervention or control group were excluded.
The included trials were conducted in China, USA, Poland and Sweden. The participants were aged six months to five years and follow-up ranged from nine to 30 months. The interventions were Duraphat and Fluor Protector. Varnish was applied to all of the primary teeth in all but one trial. The application of varnish and the use of concomitant fluoride containing products varied across trials. The control groups received no treatment, oral health counselling, or water. The frequency of treatments ranged from three months to one year.
Two reviewers selected trials for inclusion. Disagreements were resolved by consensus.