I've had two on the bottom left due to cracking. Tooth #30 (find a tooth chart on google) was very simple, easy and almost pain free. It was done by my primary dentist.
Tooth #31 was possibly the worst pain I've ever felt in 32+ years. My dentist couldn't get me numb. I had to go to an endo, and he had a hard time getting the tooth numb. He eventually found the right stuff to numb it up and started to work. He was over halfway done and hit something (a ligament perhaps) and I thought I was going to hit the ceiling. He had to numb the entire area again to complete the procedure.
If you have any doubts, go to an endo that takes his/her time and has a step-by-step plan for trying to numb the tooth.