Getting them on doesn't hurt. In my opinion, I kinda think it depends on how much your teeth need to move as to how much discomfort your in. My teeth were really sensitive for a while. My friend however said hers were never bad at all. Its nothing serious though, I threw up I was so nervous about it..I know thats stupid, but it wasn't as bad as I thought. I seriously don't know what I thought they were going to do lol. You also get use to it, so after a while your teeth don't hurt at all after getting them tightened. And if it helps, my dentist was evil and I got mine ON halloween..come on now who puts braces on a kid on halloween?!?! I couldn't eat all my candy..it was depressing lmao