I would remove the one that touches gums, first things first. If any of your teeth happens to have its roots filled with Amalgam, this qualifies as "touching gums" in my book (painful experience). I would also argue in favor removing entire teeth rather than the crowns/amalgams. A dead tooth will always retain a residue of heavy metals in its microscopic canals and there is nothing any dentist can do to seal it off. I am not suggesting something I would not do myself. This is what I did.