From the health point of view, it is 1000 times safer to extract tooth instead of just replacing Amalgam with another material.
Extraction must be done by a qualified dentist, who will make sure that no cavitations are left ... as cavitations could be a serious health hazard.
Extraction of molar teeth is more like a surgery ...
If a person is in a advanced stage of Cancer or AIDS or MS or Arthritis or Psoriasis ... extraction it is the only recommended procedure, because replacement may cause intoxication and may shorten life ... may cause death.
Amalgam replacement is for relatively healthy people ... or for people in an early stage of bad illness.