I have mercury poisoning from my amalgamam removel. I am very ill and the therapy is long and expensive. You cannot do to much research on how they remove it. It has to be vacuumed out simultaneously to the removal . You have to wear a protective mask, your gums have to be protected.
Buy chlorella capsules and start taking them a week before the removal and several weeks afterward. Make sure it is not Chinese Chlorella that is more toxisc than beneficial. The chlorella acts like a sponge in your intestines and binds some of the mercury that gets there.
If I could do it again I would have all fillings removed in one session and take 5 capsules of DMSA for 3 days starting on the day of the removal. You might need a prescription for DMSA because it is a very potent binder of heavy metals. Also, I would just have the holes filled with cement and wait a year before putting ceramic or gold inlays in. That is what I read in several German books about the procedure. There is a whole lot of literature in German out there on the topic. Good luck and be careful.