According to studies fluoride helps to prevent tooth decay by making the tooth more resistant to acid attacks from plaque, bacteria, and sugars in the mouth. It can also reverse early tooth decay.
I believe it is. Scientific studies have repeatedly shown that it is. I know a lot of people talk about how it actually causes cavities or how it is dangerous but this stuff is not supported by actual science. I think that people just like to indulge in conspiracy theories whenever the government does something like putting flouride in water supplies.
So I will go with the scientists on this one. I'm convinced that flouride helps.
The studies have shown that fluoride is fighting against forming teeth cavities but not in the way we've believed.
The fact that fluoride is forming a protective layer is not enough to prevent decay. This layer is very thin and it could be destroyed by simply chewing. It was launched a supposition that claims that fluoride has changed the hydroxyapatite from enamel into fluorapatite, that is more resistent to decay.
This supposition is in study and it has not an answer yet.