I had a root canal done years ago, it hurt having it done, the dentist was rubbish and a couple years later the tooth broke, I had to go to an emergency dentist as there was a shard of tooth beneath the gum and bits above the tooth so couldn't close mouth without pain. I went there and they said, that had to have a crown on it as the tooth was weakend by the root canal, I should say they meant it should have had one or was always going to break. My previous dentist just failed to mention it, though on talking to him about it(he was NHS, couldn't afford private at the time and getting on a NHS dentists list quickly is almost impossible(or was way back then, not sure about now) so had to go back to him.
He says he would have told me to get a crown, I know he didn't, not much to be done about it, he decides the tooth has to come out, but doesn't do extractions so I have an appointment for a really dodgy place in Southall, which resembles a barber shop when I get there. Have it injected, at least he did it well as I couldn't feel a thing but when he finally looks properly he says he's about 90% sure the tooth can still be saved and he won't remove teeth that can be saved easily. Sends me back and the original guy says "yeah I guess we can try". At this point I had no fight left in me, hated dentists, let him build up a tooth with filling around what little tooth there was left and it worked for 5-6 years.... broke last sunday finally.
I hate dentists, I'm dreading going to one severely and am still putting it off, luckily it broke above the gum line and isn't really causing any pain just yet but definitely needs dealing with.
Anyway, moral of the story being, saving teeth is good, healthy teeth are good, get a good dentist, if you aren't happy with one, leave mid treatment if you want, do not put up with a dentist you aren't happy with, ever. Also root canals probably need more treatment long term to save the tooth, a crown to maintain the strength, letting a dentist half arse it or being so put off by the treatment you don't go back till its too late are bad things.