Fluoride has another interesting property. It is useful in the molecular pairing of various heavy metal elements such as Aluminum, Mercury etc. These metals are well known toxins that can and do breach the blood brain barrier. This adds to the effective of bio-accumulation of larger heavy metal molecules that the body has a far harder time divesting itself of. (yes there are studies..and no I will not do your research for you)
It is an industrial toxin that serves no healthy biological useful purpose. So why is it so heavily used and promoted? To harden your teeth? And that makes sense to you?
BTW hygiene and a good diet do more for your teeth than fluoride ever has.