proved/proven fact

  1. It is a proven fact that fluoride strengthens growing teeth.
  2. It is a proved fact that fluoride strengthens growing teeth.
    Are these two sentences OK?

I would use #1 without the word “fact”.

  1. It is proven that fluoride strengthens growing teeth.

Sentence 1 is correct.
Sentence 2 is incorrect.

  1. It is proven that fluoride strengthens growing teeth.
  2. It is proved that fluoride strengthens growing teeth.
    Are both correct?