Out-of-order Molar

One of my backmost molars (top right) is shifted out of place in such a way that it doesn't actually interact with the molar below it. This has worried me since I first discovered it about two years ago, partially because I swear this wasn't always the case and I wonder if (and why) it's moving.

I've been pondering talking to someone about getting it straightened, but then I just read something recently that straightening teeth can be bad for your jaw and nerves. Also, I'm not sure how easy it is to straighten the back teeth like that. Aren't braces usually for straightening the front teeth?

What do you guys think? Has anyone had a similar experience?