M.B.
I had pain on and off in one of my root canals for several years. My dentist adjusted my bite and it remained and he couldn't figure out what it might be, so I went to a specialist and had it removed (50% of all root canals fail and they can be a source of focal infections). When I had the tooth removed (and a bridge put in), the root canal tooth had cracked and the stuff (gutta percha (sp?)) had leaked through. There was a tiny strand that was causing all that pain. As another poster mentioned, don't go to a regular dentist, see a specialist. And, personally, I would find another dentist, particularly given that they've not taken your concern very seriously. I had another root canal done and there is no pain from that tooth at all - that's the way it's supposed to be after the initial weeks of recovery. It is possible that your bite is off and that can cause significant pain (I had that problem with the bridge I had put in), but that's not a guessing game - they should be able to figure that out (I have TMJ and my bite needs to be carefully monitored and my dentist does that regularly). If the pain has gotten worse since they put on the permanent crown, it could be that it's not fitted properly and needs adjustment. Also, the best thing for tooth pain that I have found is the kid's liquid motrin. It goes right to the area where it's needed right away.