Fluoride is a naturally occurring element known to prevent tooth decay, thereby helping prevent cavities developing. The acid in plaque leads to mineral loss in the tooth (demineralisation), which leads to tooth decay. The formation of cavities, however, can be reversed by re-mineralisation. Fluoride can speed up this restoration of lost minerals24.
Fluoride is often found in tap water, in high enough quantities to reduce cavities, depending on which area of the country you are in (and whether you drink tap or filtered/bottled water)24. You can also get fluoride by using a fluoride toothpaste and LISTERINE® mouthwashes that contain fluoride.