Elemental fluorine is a toxic yellow-green gas that we should avoid ingesting at all costs. In most complexes, fluorine is in its -1 oxidation state, also known as the fluoride ion. While we still want to avoid ingesting massive quantities of the fluoride ion, it is less toxic than its elemental sibling.
You may be surprised to know that fluoride compounds are added to toothpaste and drinking water. Why? This element has been shown to greatly reduce cavities and promote positive oral health.20 Fluoride helps keep your mouth clean.
Does fluoride have magical powers or something? Is it emitted from the tooth fairy's wand? No, not quite. Fluorine does have chemical powers, though.
Fluoride protects teeth in two ways.20 When you're a kid and your teeth are forming and growing, fluoride from food and water is incorporated into the enamel layer. This is the protective layer on the outside of the tooth. The fluoride makes the enamel stronger and more resistant to decay.
Fluoride also protects grown-up teeth.20 It can move around a mouth in saliva and bond to the outer layer of enamel. This again helps strengthen and cleans the enamel surface. Not to mention F attracts calcium, which can help fix areas of the teeth that have started to decay.
The act of adding fluoride to water supplies is actually quite controversial.21 It was started in the 1940s after dentists stated fluoride was a "nutrient" that needed to be swallowed in order to be most effective. They likened it to a daily fluoride vitamin. It was thought the best way to get everyone to ingest this needed fluoride was to add it to drinking water.
The belief that fluoride must be swallowed in order to be most effective has since been discredited by extensive modern research.22 Currently most western European countries (97%) have banned the addition of fluoride to water sources. In fact research has shown that the ingestion of fluoride has little benefits but many risks including hampering infant brain development, thyroid gland function disruption, and possible links to cancer.22 To further complicate matters (and make the subject controversial) other research studies have shown no link between fluoridation of water and increased cancer risk.23