Twenty years ago, I moved from Michigan (a state that uses fluoride) to Mississippi (a state that doesn't use fluoride). My dentist at the time told me that I was going to end up with tooth decay if I stayed down there for more than a few years. Sure enough, five years later I moved back to Michigan and ended up with a cavity in an unusual place. My (new) dentist in Michigan was completely unsurprised.

He said there are two problems with tooth decay in Mississippi:

1. They don't use fluoride in their water. 2. No decent dentist would ever work in Mississippi.

Fifteen years later, with no changes in dental hygiene in my entire life, and I've had no other problems with my teeth. Anecdotal evidence, maybe. But that is my experience.