dental mercury removal

Due to possible mercury allergy, I am having my silver amalgam fillings removed and replaced with white fillings.  I have a couple dental crowns, no root canals.  In the process of removing the silver amalgam will the crowns have to be replaced as well.  Can there be silver amalgam under the crowns?  

[Jerome Tsang, DDS]

There is a possibility of amalgams underneath the crowns.  Some dentist use amalgams are a core buildup in which they replace the missing tooth structure with an amalgam instead of a white buildup to create structure for a crown to sit on.  

You may want to contact your previous dentist who made those crowns to really know whats underneath it.