The first thing is to eat bitter things, such as chocolate.
Or eat something that will leave a stain.
If you are uncomfortable playing with your teeth, your subconscious will think of it.
For example, you haven't brushed your teeth for n days. If you come up with this sentence in your dream, you feel that something can't be redeemed or regretted, and worry about something.
If it's to explain your dream, it doesn't matter.
I am based on my subconscious. Duke Zhou didn't study it too deeply.