Commonly used to prevent tooth decay. The fluoride is delivered topically to the tooth through gels, varnishes or mouth rinses. Systematic fluoridation is another method where fluorides are supplied through tablets or drops. The most common method is through toothpastes. All fluoridation methods provide low concentrations of fluoride ions in saliva, which produces a topical or surface effect on the plaque fluid. Fluoride prevents the decay primarily by the formation of fluorapatite via remineralization of enamel. The fluoride ions cut down the rate of tooth enamel demineralization and increase the rate of remineralization during the early stages of cavitation. Fluoride exerts its major effect by this demineralization and remineralization cycle. Fluoride also helps in fighting of dental bacteria. Fluoride has minimal effect on cavities after it is swallowed, actually fluoride does not prevent cavities but rather checks the rate at which they develop.