My eldest has Aspergers, and when he was little having anyone messing around with his mouth caused serious terror, so we switched him to a big pediatric dental practice in a wealthy neighborhood because they had special facilities and experience with disabled kids. His younger sister now goes there, too.
When DS was about 7, the appt. secretary asked when we were going to be scheduling his first orthodontist visit. We asked to see the diagnosis that showed a problem, and she said there wasn't one on record; that it was just standard at that practice for all kids to start prepping for orthodontia at age 7. When we next saw the dentist, we asked what exactly was wrong with DS' teeth that would need that kind of correction, and he looked surprised. "Oh, nothing's WRONG with his teeth; but they won't look their absolute best until the orthodontia is done." Um, no ... we are not spending that kind of money and losing that much time from work and school for ortho appts. if there is no real reason for it. (He subsequently told us that we are the first and only insured parents using that practice who declined to put a child in braces. Quelle horreur!)
FWIW, DH has perfect teeth; any time he sees a new dentist he gets asked how long he wore braces. He didn't; he just has naturally straight teeth, and actually, DS' teeth are not that much different.. Mine are crowded and a little out of line, but I've never felt their appearance was a problem. Americans are WAY too obsessed with cosmetic dental issues.