Sometime between a year and two years ago, I had one of my molars crumble to bits, necessitating a root canal and crown. That was fun times. Starting a month or two ago, that very same tooth started acting tetchy. Then one day a few weeks ago it went so thermonuclear that I couldn't see straight. Unfortunately, my pain tolerance allows me to let things get this out of hand before I do something about it.
Long story short, the original root canal - though it was a fine job - got "re-infected" and required "retreatment". Said retreatment was completed roughly an hour ago. I went to a new guy who specializes in endodontics, and I have to say I'm impressed. The whole thing took about an hour and I was falling asleep through half of it (which I attribute to a total lack of odontophobia and perhaps a very low-grade case of narcolepsy -- stress makes me drowsy ;) ).