I actually had my dentist get defensive and turn all red and start sweating when I told him I did not want my broken filling repaired with more mercury because it was poisonous.
He gave me the riot act about how if I had it taken out my teeth would be sensitive and I might lose them. (What? There are already lost and were the day they were filled!) And any teeth with metal in them are so sensitive to cold/hot they are painful. And of course...there is "no evidence" according to him. I told him he was entitled to his opinion and I walked out! The second dentist tried to sell me a root canal. Told me how tragic it would be if I lost a molar. Mainly, any doctor or dentist I have seen about this, denied anything! Funny, they all had mercury fillings as well.

Here in the US there are no commercials. No warning signs, nothing. Most dentist won't admit anything, they are under threat from the ADA of losing their license if they say a word.