Fluoride makes your teeth more like shark teeth!

Sharks have enamel that is nearly pure fluorapatite. When you drink fluoridated water and brush your teeth with fluoride toothpaste, fluoride remineralizes the cavity-prone carbonated apatite in your teeth and forms a mixture of fluorapatite and hydroxyapatite.
Fluoride is the major ion of fluoride which is the 13th most abundant element on earth.

It is a naturally occurring element all over earth.
And finally, did you know?
Most water contains some fluoride but usually not enough to prevent tooth decay.

Community water systems can add just the right amount of fluoride to local drinking water to prevent cavities.