Fluoride Varnish for Caries Prevention in Preschoolers: An Overview of Reviews

This study aimed to overview the available evidence from systematic reviews (SRs) on the effects of fluoride varnish (FV) for caries prevention in preschoolers.

Systematic reviews, with or without meta-analyses, of randomised controlled trials (RCTs) and quasi-randomised trials evaluating the use of FV in preschoolers to prevent dentin caries compared to placebo, standard care, or no intervention were included. The search was last updated in July 2025 across eight electronic databases. Two researchers independently assessed eligibility and extracted data, resolving disagreements by discussion or with a third researcher if needed. The methodological quality, risk of bias, and certainty of evidence of the SRs were assessed using AMSTAR-2, ROBIS, and GRADE, respectively. The results were synthesised descriptively.

Fourteen SRs published between 2001 and 2023 were included. Six SRs reported insufficient evidence to conclude on the effectiveness of FV; six concluded that FV is effective; and two suggested that FV provides a probably irrelevant clinical benefit. One SR had a high methodological quality, two had low, and 11 were rated as critically low. The risk of bias was considered low in three SRs and high in 11. The certainty of evidence ranged from moderate to very low, with the risk of bias being the criterion that most contributed to downgrading it.

Most systematic reviews on the effectiveness of fluoride varnish in preventing caries in preschoolers are of critically low quality and high risk of bias, with conflicting findings. Systematic reviews that included more recent studies with lower risk of bias indicated that fluoride varnish provides relatively limited or no additional benefit to children who use fluoride toothpaste. Therefore, the routine application of fluoride varnish in preschoolers should be reconsidered.