Comment by jandrewrogers

I would be really surprised if dentists had much expertise on the impact of fluorine on physiology or the mechanisms of action for its toxicity. They know what it does to your teeth, and maybe that it is known to have positive effects for cardiovascular health, but that is about the extent of it. The systematic effects on the rest of your body are outside their domain.

Chemists who work in fluorine chemistry on the other hand have to become experts on the biological effects of fluorine exposure. Small and seemingly innocuous exposures can do a lot of damage and kill you, though not in a way that lends any support to the idea that municipal fluoridation will harm you. If you do understand how it kills you (basically by being exceptionally narrowly focused on making free calcium ions and to a lesser extent magnesium ions biologically unavailable), it is hard to describe a chemically plausible scenario that somehow avoids this basic fact of chemistry. Fluoride behaves the same way outside the body.

Municipal water exposure is far below the noise floor for fluoride. Food has far higher levels of fluoride than municipal water and the body has ample excess calcium and magnesium to absorb the loss of bioavailability of a microscopic amount of those minerals. Humans consume calcium measured in grams per day, multiple orders of magnitude more than can be lost via municipal fluoridation. Natural dietary variation will have a far larger effect.