The American Dental Association (ADA) reports that topical fluoride varnishes should be applied every 3 to 6 months for patients at higher risk of developing dental cavities and tooth decay. A dental professional will guide each patient to determine if applications every 3 or every 6 months will work best for their individual situation, which is based on: risk of cavities, re-care frequency, and symptoms of dentin hypersensitivity.