Is amalgam possible under crowns?

I have three crowns, a metallic one and two porcelain(with metal under them)
Could the teeth be covered with amalgam? 4 months ago I finished replacing my 10 Amalgam fillings, but I'm not sure if I have removed all of them.
My concern is about the crowned teeth now.

I live in Greece.Here dentists don't know a lot about metal toxicity.I had a panoramic x-ray so as to see if the crowns did have Amalgam under them. The dentist couldn't tell me for sure. The only I remember is that the oldest crown which was put at the age of 13 (28 now) probably hasn't any amalgam. But the other tooth that had to put a crown was so heavily damaged, that the dentist had to gather its pieces so as to put the crown. I can't remember what he adhered them with.

Can anybody tell me whether I should be concerned about the crowns or not?

Last month I had a hair test sent back from USA. The Mercury level was a little beneath 0.18, within the reference range.Does that mean that I'm a slow excretor or that my Hg is almost gone(really Hg toxic before Amalgam replacement as blood tests showed)??

Thank you very much.Really appreciate any thoughts on that