A Comparison with Fluoride Fluoride in drinking water and oral care products has had unquestionable influence in reducing tooth decay worldwide. When it was first introduced into U.S. water systems, the reduction in new caries in schoolchildren was as high as 35-60%. But excessive intake can lead to dental or skeletal fluorosis, and as a result the amount permitted in oral care products and community water systems is controlled. Nanoparticle hydroxyapatite, though not widely known, has been used in toothpaste in Japan for almost three decades. In field trials leading to its approval as an anticaries agent in 1993, the reduction in new caries among Japanese schoolchildren using the nanoparticle hydroxyapatite-containing toothpaste once daily over a period of three years was 36-56% compared with children using a non-hydroxyapatite containing toothpaste. Hydroxyapatite is a biocompatible substance, used widely in bone grafts and health foods, and can be swallowed without concern, including by children. It has no known toxic or negative environmental effect. Fluoride, though not a remineralizing substance in itself, strengthens the teeth against decay by promoting uptake of calcium and phosphate ions from saliva and other sources into the enamel (remineralization). At the same time, it forms a new substance, fluorapatite, on the tooth surface, more resistant to plaque acids than the enamel's original hydroxyapatite. The most active element in the periodic table, fluoride is supplied in toothpaste in the form of compounds such as sodium fluoride (NaF) or sodium monofluorophosphate (MFP). In contrast Nano mHAP, supplied in the form of nanocrystals, is a calcium phosphate almost identical chemically to the hydroxyapatite of our teeth. It has been shown in vitro to remineralize subsurface demineralized lesions and fill microscopic surface fissures, restoring both surface and subsurface enamel, and to bind and precipitate out of solution cariogenic bacteria such as mutans streptococci. Unlike fluoride, Nano mHAP adds nothing 'new' to the teeth, but by restoring and maintaining the enamel's mineral density and surface smoothness - making it glossier, more translucent and less susceptible to plaque attachment and to decay - Nano mHAP can be used with confidence to protect not only the health but also the beauty of our teeth.