too much flouride is actually really bad for your teeth; brown spots/pits I think. It's why children's toothpaste has minimal flouride, because they swallow a lot of it.
adults: don't swallow your toothpaste.
adults: don't swallow your toothpaste.
People talk about how the fluoride in tea can help prevent cavities, but on the darker side... just imagine having all your food come from that sort of fluoride-rich soil.
I was curious as to where the fluoride was coming from, and this report: https://sci-hub.ee/https://link.springer.com/article/10.1007... seems to indicate that the mines increase fluoride in grounderwater due to exposing carbonates which then can dissolve, kicking off a change in pH and various other reactions that release fluoride from the minerals it's otherwise locked in.