Fluoride varnish compositions for temporary application and adhesion to a person's teeth. The composition includes a carrier comprising a resin and an adhesion promoting agent comprising an alkyl phosphoric acid. A fluoride ion source (e.g., a fluoride salt such as sodium fluoride) is dispersed within the carrier so as to provide biologically available fluoride ions to the tooth tissue being treated. The composition adheres only temporarily to tooth tissue (e.g., for a period of at least about 4 minutes, but not more than about 1 year), after which the composition spontaneously wears away as a natural result of the action of the tongue, saliva and/or other factors.