well i don't play trumpet, i play trombone, and i've never had braces, but i've heard its pretty hard to adjust your obiture(sp?) but one of the things i do to work on range is about 5 minutes before i start practicing, i buzz on my mouth peice so my lips get warm. plus this way you won't press into the mouth peice when you get your trumpet up.
hope this helps!! 3nodding