What is the duration of fluoride varnish on patients’ teeth and how does it compare to foam?

Fluoride varnishes harden on contact with saliva, thus allowing them to remain in high concentrations on the enamel surface for 1-7 days, instead of 10-15 minutes as is the case with gel and foam. Vella 5% Sodium Fluoride Varnish with Xylitol (Preventech) is a new fluoride varnish that is indicated for the treatment of dentin hypersensitivity and as a cavity varnish.