Yeah, I'm going through a dental nightmare right now of sorts...
I had an old crown on a root canal I had done around 20 years ago come off... When it came off I was eating and I bit down and it chipped a tooth under it.
So I find a new dentist near me (old dentist has long since retired), luckily he seems pretty cool. He tells me he needs to redo some of the build up and put a new crown on the one where the crown came off, so cool.
While waiting for the perm crown to get in the chipped tooth becomes a broken tooth as it had a filling I got when I was a teenager in it and suddenly I had half a tooth there. Go back in... He's able to "salvage" the tooth by essentially root canaling it. so now I have a new root canal on the bottom. My molars are moderately messed up because my wisdom teeth, when they came in, came in perpendicular essentially, and did damage. Also seemed to have damaged my nerves around there because almost nothing causes me any form of tooth pain.
While doing this he does a general check up and xrays of the whole shebang. On the other side of my mouth he sees where I got a root canal when younger (crappy teeth seem to run in my family no matter what, Dr once postulated it might have been something genetic with calcium uptake, who knows...). And there was a small gap near the seating where the crown met the tooth. He tells me it's an "eventually you'll want to get that looked into, it might cause problems".
"Eventually" caught up to me last week. Seems that gap allowed a small amount of decay to start inside the crown, where it ate away at the underlying tooth. That crown pops off with the "build up" the old dentist did in it. (starting to wonder if my old, now gone, dentist was a shitty dentist...) The tooth feels like just an empty space to me with a tiny ridge of the tooth exterior around the edge. As a temp fix I throw down some instamorph. That's a plastic that goes molten around 150 degrees, incredibly useful when I'm tinkering and need to make a quick plastic cover/part, and I saw a post on it where a hockey player used it to make a temp bridge when he lost an incisor until he could get to the dentist. So I melt around a fingernail sized piece of it, put a small ball of that inside the crown, press it down into place, smooth the extrusion around it, and it's held up perfectly and working.
Go back into dentist. I want him to take a look and figure out what happened. Find I can pop the crown and instamorph binding out like it was essentially a bridge. He is amused at how well it works. Looks more in depth... He'll need to clean up some of the decay, but thinks there's enough tooth left in good condition to save. But my dental insurance is tapped for the year. So he asks me if I can put the crown back in with the plastic, which I do there since he was able to microwave me a glass of water to remelt it. Now I have an appointment first week in January to get that one fixed.