My dentist did a root canal on a much -repaired back molar, preparatory to crowning it. It was painless but also the longest dental treatment I've ever had in my life. It was an complex root.
After the root canal filling had "settled", xray showed it had a small spot of infection at the very top end, and he would not proceed with the crown until the infection resolved. It never did :-( and about a year in the infected site was beginning to feel a bit of intermittent sensitivity in the top of that gum .
So last week I had the whole thing extracted (no pain, but took a while and pretty difficult/stressful. He found an infected cyst right at the far end of it, which drained messily for 24 hours. It left the biggest messiest extraction cavity I've ever had; sent home with instructions for salt water rinses, and two weeks of soft food only. One week in and I'm longing for something chewy. But the cavity has closed well and I can tell there's no trace of tenderness where the infected spot used to be.
Dentists suggestion for next move is an implant; but after this experience of infection I'm not going to risk another failure. .
The other option is to get an additional tooth on my dental plate.For that, he wants to wait 6 months until my jawbone adjusts to the gap.
So, sorry to tell you, not a good experience of root canal and it's put me off ever doing one again. Another time I'd prefer simple extraction of ancient tooth right away.