I want to caution anyone who is offered the latest "Six Month Smiles" procedure, which is supposed to straighten crooked teeth in a matter of six months, DON'T DO IT! I went to a dental practitioner (who probably did a three day course) and now my teeth are more messed up than before! He pulled my upper and lower arches forward, out of their natural shape so they are now very narrow and long. It's caused my whole face to change as well as my profile. Everything is much fatter and pushed out.
I've finally made it to a qualified orthodontist and after having those "Six Month Smiles" on for half a year at 19, I have to have conventional braces for another two years!
There's a reason orthodontic treatment takes so long! Take it from me, if you're considering braces, the best thing to do with your money is to invest it in someone qualified, and a treatment that is going to give you everything you require, rather than compromising aesthetics for straight teeth.