question: I had a root canal about 5 weeks ago and a temporary was put on.   I had to wait for the healing of the tooth extraction next to the one with the root  canal to be fitted for a bridge and crown.  About 2 or so weeks ago, I started feeling a dull pressure under the temporary.  Last week I was in pain and am now on penicillin.  X-Rays were taken but showed no infection, however earlier X-Rays on the root canal of the extracted tooth also showed no infection, but the dentist discovered it when he started and had to stop until it cleared up. My question is can bacteria get in under a temporary?   If not, how can a root canal that felt OK for 2 weeks suddenly become painful?   Thank you.