Fluorides are minerals present in our teeth and bones. Fluoride is used in the prevention of tooth decay as it promotes the remineralisation of the tooth enamel.
The use of fluoride is controversial and it is claimed to be toxic to humans. However, it is safe to assume that the fluoride concentration in common toothpaste is not sufficient to cause symptoms of poisoning. Fluorides form a protective layer of calcium fluoride around the teeth which protects the enamel and neutralises acids. Furthermore, fluoride penetrates bacteria and interferes with their metabolism, inhibiting their acid production.