I used to be taken to "The Clinic" when I was about 9 for free dentistry. My two front teeth were slightly protuding so "The Dentist" gave me a huge (to me) gumshield to wear while sleeping. After the novelty of pretending to be Rocky Marciano wore off I went to sleep with it in and woke up some time later with it halfway down my throat. My teeth unprotruded of their own free will and the gumshield went in the bin.