All a dentist would do would be to wipe off any large debris (as long as noxious chemicals aren't involved, you don't really even want to wash it) and then stick it back in the socket. Maybe pack some cotton rolls around it to keep it in one spot for the first 12 hours or so. Doing this on-scene ASAP is strictly better than waiting until you get to a dentist.

Would it still take root if it was placed in backwards? If it was someone else's tooth? a particularly well shaped rock?

It depends, but there's an issue of biocompatibility similar to any organ transplant. So no, a rock wouldn't work. The backwards tooth though is interesting - my guess is if it would fit it would stick (although it would definitely fuck up your bite).

https://myhillsdentist.com/blog/why-dont-we-do-tooth-transpl...

I wouldn't be surprised if a backwards tooth could remain viable. This is the sort of error that would be noticed immediately by any conscious patient, however. A backwards tooth would mess up occlusion. Few people would ignore the fact that they can't close their mouth completely.

And that's just the beginning of the story.

The same thing happened to me. 10 year down the line the inside of the tooth has been mostly absorbed by the bone leaving it fragilized (which, according to my dentist, is a common occurrence in those cases).

I just spent a year working with my dentist to replace the teeth with an artificial one.