But honestly, I'm not sure I understand the pain thing. From my 3 or 4 root canals, here is how it goes at my root canal specialist:

First you get all set up by the amazingly beautiful dental aide.

Then you get shot up with a bunch of novacaine, lydacaine, or some other caine. You feel zero of the rooting.
After the rooting the tooth nerve is gone. There is no nerve there to feel pain. In my experience a root canal is less painful than a regular cavity repair.

Immediately after the procedure, I pay the lady and drive to work and work the rest of the day. End of root canal event. total time involved including driving to and from the dentist perhaps 1.5 hours. There are no pain pills to take, no nothing. A root canal is the closest thing you can get to a nonevent. A CLEANING has more residual discomfort than a root canal! Probably because there is no nerve anymore to feel pain.

Your experience may vary.