I live in a town where a huge amount of people seem to have bad brown teeth staining. I asked my dental hygentist about it & she said it's cuz there's so much flouride in the water here. Then she proceeds to offer me a flouride treatment. uh, NO thanks. If flouride does actually darken teeth, I would think Amish avoid flouridated water if their farms use well water which would be filtered thru the ground...? shrug