I had a tooth with decay under the amalagam. He said he had to drill very close to the nerve. About a week after I couldn't put pressure on that tooth as i would get a big nerve shock. I went back and he said it needed filing down more so he did. It improved slightly but I needed to go back and have more filing done which I never did.
I put up with that tooth hurting for years until it has finally, naturally moulded into the right shape it needed to be.