I spent another day with the dentist. Same ol same ol by now, right?
Not so much (which you probably surmised). The dentist was doing the crown prep for that root canal tooth when she saw on the tooth next to it a ridge that seemed a little dark. This is a tooth that was fine on X-ray, not slated for anything on the treatment plan. The dentist thought she'd polish the ridge off, though, just so there wouldn't be a nifty potential home for bacteria when the crown is in place.
Long story short, it wasn't a normal tooth ridge, it was a crack. A little digging uncovered decay growing in it. Why didn't it show up on the X-ray? I have no idea. But that tooth is now all cleaned up and filled and all that. Her decision to go a little beyond the plan of the day probably saved this tooth. Plus she now has notes in my records on specific things to watch for that probably wouldn't be prioritized as highly otherwise.
So I'm stoked. I feel like there's a little hope that maybe I won't have to continue the PTSD loop forever.