Sodium fluoride (NaF) is a chemical compound and medication.As a medication it is primarily used to prevent tooth decay in children older than 6 months in areas where the drinking water is low in fluoride. Sodium fluoride is used as a liquid, pill, or paste by mouth with this use being known as fluoride therapy. Normal doses may occasionally result in white marks on the teeth. Excessive doses can result in brown or yellow coloring of the teeth. It is believed to work mostly through direct contact with the teeth.Sodium fluoride is a colorless solid. It is most often made by mixing fluorosilicic acid with sodium hydroxide.