I've had the teeth falling out dreams a lot and written music about them; I enjoyed this take on their layers of meaning and purpose a lot. As far as they sit between subject and object/body and mind, perhaps they can be related to the "third force" idea of Gurdjieff, if you're familiar with him.
That's a very common dream! My girlfriend has them a lot. I hadn't considered that Gurdjieff's third force might have anything to do with this...hmmm...