I am hoping someone will help me with educated guesses.

I had gone to the dentist a while back, and he cracked couple of my teeth whilst performing fillings. Had crown done on both the cracked teeth, but root canal was not done prior to crown. They both hurt. So for one of them (most bothersome), it had become very painful upon biting on food (hard to semi hard, not soft), and for a short while become extremely hot sensitive (which has since reduced to a great extent). Anyway, after a first root canal, it still hurt, so was referred to a specialist, who performed a root canal again and saw a 4th canal and performed root canal.

However, the tooth is still hurting after about 4 weeks. It is the outer edges of the molar that hurts. Mostly the side towards the cheeks, but sometimes the inner side as well. Dentist says it could be a crack, but cannot see anything on x-rays...Says a crown covers the tooth so it is impossible to see.

What I would like to know is what other possibilities could it be. The diagnostics is everything. Removing the tooth is something I would definately like to avoid. Could the crown have gone in incorrectly? Could be a crack? What else could it be? Has anyone been in a similar situation?