Multivitamins provide essential vitamins and minerals that are not taken in to the body through diet. Fluoride strengthens tooth enamel, which helps prevent dental cavities. In most major U.S. communities, fluoride is put into the water supply. Multivitamin with fluoride is used as a supplement to the diet of infants and children who do not receive adequate fluoride through drinking water. Multivitamin with fluoride is also used to prevent tooth decay in people treated with radiation, which may cause dryness of the mouth and increased risk of tooth decay. Multivitamin with fluoride may also be used for other purposes not listed in this medication guide.