thank you all for your responses. i did a little researching and backtracking from my previous dentists, got x rays back from 2000, and of my 3 crown, it looks like 2 are not likely to have mercury underneath. one, however has a titanium post, and a gold/porcelain crown. the 3rd, i'm not sure about. has anyone read hal huggins..."its all in your head" book? i just ordered it.