I have always heard that those dream symptoms are related to either grinding your teeth or stress, but have never seen any actual proof.

The only thing I can offer is that I used to love going to the dentist (didn't have my first cavity until 18 yo and thought the cleaning was fun), and I have had dreams with my teeth twisting, crumbling, falling out, and shattering for as long as I can remember. So I don't know if fear of the dentist would be one. If that were the case I would have way more dreams about tornadoes (which I am phobic of) than I do of my teeth falling out!

I do bite my nails and sometimes worry I'll chip a tooth on my nail like a friend did back in 8th grade. That's the only think I can really think of. Maybe it's just because we brush our teeth twice a day?