I think we misunderstood one another
The tooth which is resorbing is amalgam filled
If Im to save the tooth, the amalgam in that tooth will need to be drilled, it was that which I was speaking of when I spoke of rubber dams / isolated air suppli
Neither would be necessary if the tooth was being extracted, but If there is any chance to save the tooth I would like to
The best I think will be to do it your way - as you would accept it. There are always ways for everything. It is you to choose what is the best for you.
My oppinion - treat the clenching or grinding, and live your life happy.
If you are not satisfied, and want to save as much from the tooth as you like, then drill away the amalgam, slowly little by little (protected with the dam if you wish) and replace the amalgam with what you wish - monomere releasing polymers, breakable and indurable glas ionomers or expensive onlays.
If you are not satisfied, and you want to remove the filling in a single block, with the cost of sacrificing much hard dental tissues, then you may use laser dentistry, which is much expensive. Some wavelengths ablate away the dental tissues, but are being reflected from the amalgam and don't ablate it (Er:YAG and ErCr:YSGG dental lasers). It is possible to ablate away only the hard dental tissues, remove the amalgam in a block and leave your tooth with a large crater, which further will be recovered somehow with overlays or with a dental crown. It is possible.
Even if you decide to pull out the tooth, which is the worse accoring to me, and place an implant it is also possible.
You may even pull out the tooth and simply remain with one tooth less. You may ive 100+ years even without your teeth. If you have received some amalgam paranoia, and only removal of the amalgam will stop it, then it should be medically acceptable to sacrifice the tooth to heal your paranoic brain.
There are more solutions, I would say maybe infinitely many solutions, and it all depends on what exactly, very exactly, would you like.
My advice:
Visit neyrologist and live your life with the amalgam. I have at least 10 amalgam fillings, my brain is fine, and my life is happy
Plan B
Drill out the amalgam with a standart burr and a dental dam, fill the gap with something on your choice, and live happily ever after.