I sucked my thumb for a long period of time. I had a mouth piece put in around age 8 to stop me from doing this and to try to align my teeth up. About four years after the mouth piece was taken out, I developed problems with my jaw. I went through a winter season where my jaw would get locked and I would have to move my jaw around for hours to get it back to normal. After that one season it hasn't returned back to normal. Now I can't open my mouth as wide, and my jaw pops everytime I open my mouth. It is liveable so far, but I often wonder if it will return.