A Cochrane systematic review of fluoride gel found good evidence to support its dental caries-preventive effect (Marinho et al., 2003b). The weighted mean reduction in DMFS increment in the permanent teeth of children in the 14 placebo-controlled clinical trials included in the meta-analysis was 21%. However, little information on its effectiveness in the primary dentition of
young children is available. Because a relatively large amount of fluoride is present in the gel delivered in a tray, risk of excessive ingestion by young children, leading to mild toxic side-effects, is a potential problem for its use (Adair, 2006).