If your dentist is cooperative, you can have her (or him) make one of your teeth fractionally larger, and it will stop the cutting teeth (incisors?) from coming all the way down, and effectively stop them from being able to bite the inside of your mouth. The only danger is cracking the bigger tooth, so they are reluctant. Oh, yes, chewing like that is a stim and a typical (in one form or another) AS tendency under stress.
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A smile can be infectious. Let's hope they never find a cure.