Fluoride

Fluoride is an inorganic anion of fluorine with the chemical formula . It contributes no color to fluoride salts. Fluorite is roughly 49% fluoride by mass, making fluoride the main component of fluorite apart from calcium ions. Fluoride contributes a distinctive bitter taste, but no odor to fluoride salts. Its salts are mainly mined as a precursor to hydrogen fluoride. Although it is classified as a weak base, concentrated fluoride solutions are corrosive and can attack the skin.

Fluoride is the simplest unary fluorine anion, the other being the tentatively investigated difluoridofluorate(1-) anion. Its salts are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Structurally, and to some extent chemically, the fluoride ion resembles the hydroxide ion. Fluoride ions occur on earth in several minerals, particularly fluorite, but are only present in trace quantities in water.

Cavity Prevention

Fluoride-containing compounds, such as sodium fluoride or sodium monofluorophosphate are used in topical and systemic fluoride therapy for preventing tooth decay, but the exact biochemical reason is unknown. They are used for water fluoridation and in many products associated with oral hygiene. Originally, sodium fluoride was used to fluoridate water; hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2SiF6) are more commonly used additives, especially in the United States. The fluoridation of water is known to prevent tooth decay and is considered by the U.S. Centers for Disease Control and Prevention to be "one of 10 great public health achievements of the 20th century". In some countries where large, centralized water systems are uncommon, fluoride is delivered to the populace by fluoridating table salt. For the method of action for cavity prevention, see Fluoride therapy. Fluoridation of water has its critics (see water fluoridation controversy). Fluoridated toothpaste is in common use. Meta-analysis show the efficacy of 500 ppm fluoride in toothpastes. However, no beneficial effect can be detected when more than one fluoride source is used for daily oral care.