Years ago I went to a chiropractor when my jaw was out of place. He used this little "thingy" and popped my jaw back into place. Took about 10 seconds.
I left his office, got in my car, started driving home, yawned, and my jaw popped right back out of place.
First off, thanks you just made me yawn!
Not many things in the world are fix and forget. The worst things for my wife with her TMJ was yawning and the dentist, with keeping her mouth open for long periods, or trying to bite into a big thick burger or samich.
Its like the old HeeHaw skit, "doc it hurts when I do this", his answer, "well, don't do that."
One of the explanations the Chiro gave us is, when something gets out of place, the body "learns". After correcting the misalignment, we need to retrain the body or it will revert back to what it learned. He always tells us after getting a back adjustment, to get up and walk, don't just sit and let your back revert back to misalignment.
The Chiro actually did cranial chiro, were he stuck his fingers in her mouth and did adjusting, I do know not many are knowledgeable in this technique. The "thingy" to put your jaw back in place is just part of what you need. I'm sure everyone one is different and YMMV.
Try to keep you mouth closed as much as you can when yawning.
I know its not as satisfying as a big ol' triple cheeseburger yawn, but better than a jaw pop!
Good luck and hope you can find something that helps!
Rick