Imo getting the amalgams replaced in two or 3 appointments spaced a few weeks apart (or even a month apart if you can tolerate the wait) makes sense. Getting novacaine in more than two quadrants in one day is not a good idea. If you are so chemically sensitive, then getting novacaine in more than one quadrant might make you feel very sick. There is also the mercury exposure, which will be overwhelming if all are done at once. if each quadrant is done a month apart, you body will detox quite a bit from the spike in mercury before your next exposure. I had 22 amalgams removed, and only have 3 left. I had them removed over a period of around a year.