Fluoride

Fluoride refers to the fluoride ion (F−) and to compounds that release fluoride. It is commonly encountered as fluorides, such as sodium fluoride or fluorosilicic acid, used in dental products and public water supplies. Fluoride is a natural constituent of the Earth's crust and is found in water, soil, rocks, and foods. Mineral sources include calcium fluoride and fluorapatite.

In dentistry, fluoride is used to reduce tooth decay. Methods include adding fluoride to drinking water (water fluoridation), incorporating fluoride into toothpaste and mouth rinses, and applying topical varnishes or gels in clinical settings. Mechanistically, fluoride promotes remineralization of early enamel lesions and inhibits demineralization; it can form fluorapatite, which is more resistant to acid attack, and can affect oral bacteria metabolism.

Safety and exposure: When used appropriately, fluoride is considered safe and effective for caries prevention. However, excessive fluoride during tooth development can cause dental fluorosis, and long-term exposure to high fluoride levels can cause skeletal fluorosis. Ingestion of large amounts of fluoride preparations can be harmful; toddlers should use only a pea-sized toothpaste, and children should be supervised to minimize swallowing.

Regulatory notes: Public health guidelines vary by country but typically aim to balance caries prevention with safety. In many places, drinking-water fluoride levels are around 0.7 mg/L.