“My impression is that most dentists are not strongly marketing the replacement of amalgam fillings because people might start asking: “What were you putting into our mouths all these years?””
Another reason to consider, removing the old amalgam fillings may actually increase the mercury exposure of the patient (even drastically). So, to replace old fillings, fo no other reason to remove the mercury amalgam, may actually have a negative benefit.
That's a given, but chelation therapy, both intravenous and oral, plus the intake of selenium can dramatically decrease mercury content in body tissues.
IMO, mercury does escape the amalgam fillings during chewing and deterioration due to natural enzymes present in the mouth.
The WHO literature and studies done by the Canadian dental association in animals shows that mercury poisoning occurs with installing mercury amalgams in teeth.