I'm currently wearing the one for an underbite. Its the one where its practically in front of your face and rubber bands are put in front of you. Yes, the one im wearing is uncomfortable. I'm wearing it as i answer this question!!! You must sleep at night with it if its the one i have, sometimes it'll turn sideways and its gonna hurt like a b***h when you wake up. I dont like it at all, your teeth will be aching the first couple days but once your used to it, you'll be fine. Remember, no pain no gain.
I am wearing one. It all depends. if you were it as long as you are SUPPOSED to it DOESN'T hurt. but if you are like me and keep putting it off and then you wear it it is uncomfortable for like 5 minutes. When i fist got it i was only able to wear it for four hours. then like 2 months later i was able to wear it all day. after a certain amount of time (i mean overall and not in a day) it feels like you don't have it in. i know the way i typed this it sounds very confusing but i hope that you do understand what i am trying to say! :) PEOPLE OVER EXATURATE THE PAIN! (THERE IS NONE IF YOU WEAR IT LIKE YOU ARE SUPPOSED TO! :) ;) )