granny grump - "It seems that every other teenager I see is wearing them - are their teeth that bad or is it just that dental treatment has changed so much"
The latter - dentistry has moved on in leaps and bounds from when we were kids.
The best you could hope for when you were growing and your dentist was good enough to spot overcrowding, was to lose four teeth with gas!
All my girls have worn braces - Charlee the youngest could see the benefits for herself. Tanya the oldest wore hers religiously and has beautiful teeth, Kerri was less diligent, and her teeth are slightly crooked, Charlee decided her older sister's option was best, wore hers religiously as well, and has beautiful teeth.
The less said about mine, the better, but the top ones look nice after some crowns and bridges. Their mum has always had nice teeth, even after the 'four out' as a child, which I had too.