I taught in a rural area without flouridation. I would be more willing to believe or bet that the kids with problem teeth are from families with poor diets, education about oral hygiene, etc. My observation was the kids from "better, more with-it" families had better teeth.
The area I lived in with no floridation in the water was Silicon Valley California.. this was hardly a bastion of uneducated, poor diet po folks.
Floridation works, the evidence is overwhelming that it does work.