I'm sure if you are feeling pain in dream it means that you are felling pain for real...
Also, related story:
I once came to a free dentistry for the same operation as yours. They put arsenic there to kill the nerve and then injected anesthetic. But it didn't work, I can still feel my teeth. They started doing the thing and no kidding it was a torture, but I was a very patient kid, so I was just laying crying and scratching myself. I told them it is painful, but for some reason they ignored me. It lasted like 20 minutes, then they sent me to cabinet nearby to make an x-ray. Then they tortured me a bit more and let go, and now I will never go to a free dentistry again. Then, like two years later when my teeth was still hurting for some reason I found out that in my tooth is broken metal tool thing that they used, funny, right? It's not that bad actually, so don't worry