I’ve had nine root canals. Root canals don’t hurt. The pain BEFORE the root canal is what people are talking about.
First the dentist will give you novocaine. This is the best part, the pain stops 
Then he will drill and he goes into the tooth and removes all the pulp and nerves from the tooth’s root. Depending on the tooth you can have one root or four roots. If you feel anything, tell the dentist. One time my dentist had to shoot novacaine, into the canal.
Then he takes a little file and he cleans out the pulp and nerve. You’ll here a slight squeek and you’ll feel it but no pain. Then he seals the tooth up.
You have to come back in a week. You may or may not get antibiotics.
Then on visit two, he shoots you with novocaine again and he he goes back to the tooth and re-drills. He then uses the file and cleans out the roots of the tooth again. A really badly infected tooth may require this step twice. But usually not.
Then comes the worst part. No it doesn’t hurt. He has to make a mold for your crown. He takes some substance, which is like modeling clay and puts it in your mouth (yech). He then tells you to clamp down and bite for FIVE minutes. (again YECH!!!) Then he takes the clay out and send it to the lab for your crown model.
It’s very important at this stage to talk to your dentist about the color of the crown, unless your teeth are white. Remember the crowns do NOT discolor. I had my first root canal in 1997 and today it’s very obvious which teeth are crowns. There still very white. So eventually even though there’s nothing wrong with the teeth, I’ll have to get my teeth whitened or my crowns replaced.
Then once again, Mr Dentist reseals up the root canal and you come back in a week
Then the dentist will novocaine you again and drill the shape the remainder of the tooth for the final fitting. He pops the crown on and has you bite and makes sure the crown fits. He may do minor adjustments to the crown. They should be very minor. If he makes any major adjustment to that crown, tell him you want a new crown. A minor adjustment is fine, but a major means the dentist screwed up.
Then when that is done he pops off the crown and puts permenent cement on. Then he pops the crown back on and it takes a few minutes. Then he flosses off the excess cement and your new tooth is good to go.
A few things to remember. First of all a porcelain (white) crown is a lot and I mean a LOT tougher than your tooth. So it’s likely the tooth directly above it, especially if it’s a molar, will also need attention, because the porcelain crown will wear the tooth down a lot faster.
A gold crown doesn’t do this. But obviously you don’t want that if you can see it. But I would highly recommend a gold crown for a molor. It’ll cost more but save you in the long run.
A root canal also can fail. There’s no guarantee. I had two of mine fail within a year. The other seven have held up over ten years. So you don’t know.
Now is the time to get a dentist that will treat your “whole mouth.” If you have bad teeth and bad gums and are just going to wind up in dentures anyway, you don’t want to be putting good money after bad.
A root canal is worth it but because it’s costly you have to think of things like this