This mineral primarily exerts its well-known anti-caries effects by reducing demineralization and enhancing remineralization. When fluoride is present in low concentrations in saliva and plaque fluid, fluoride ions are likely to be incorporated into the remineralizing surface of the lesion, making the repaired section higher in fluoride than it originally was. The material formed on the surface of the lesion is more accurately called fluorapatite, a more stable and less soluble material that is protective of the lesion body underneath. It also binds firmly with calcium, making it less likely that calcium ions are pulled out of the tooth and into the solution. When saliva and plaque fluid is supersaturated with respect to fluoride, and when fluorapatite has formed, it has been found that damage to tooth structure does not start occurring at a pH of 5.5, but rather at a more acidic 4.5, emphasizing fluoride’s protective effect. The overall effect is reduced dental demineralization as a result of the protective outer layer of fluorapatite. If fluoride is not available, the oral environment begins to favor demineralization.1

In the United States, fluoride is most commonly delivered systemically via the water supply, or topically in the form of over-the-counter or prescription fluoride dentifrices and mouthwashes. In more serious caries cases, professionally applied fluoride varnishes, gels, foams, or slow-release applications may be necessary.