What are the differences between fluoride gels/foams versus 5% fluoride varnish?

The FDA does not recognize a caries prevention claim for fluoride varnishes. It’s approved for use in hypersensitivity only. However, its use in Europe over the last 30 years and more recent lab studies have shown it to deliver an equivalent amount of fluoride on the tooth surfaces. Because it’s painted on versus the tray technique it is much easier to use on children under 6 year of age. And because it dries on the tooth surface it reduces the chances of accidental ingestion on small children. For this reason, it has displaced foam as the product of choice for this patient population.