Invisalign -- a removable, clear polyurethane device that fits over the teeth -- gets a lot of press as an orthodontic option for adults who want to avoid the maligned "brace face" look. But it's an alternative for teens, too. All the wearer's permanent teeth have to be in, so orthodontists usually don't recommend it for patients younger than 13. There's also the responsibility factor: Invisalign has to be worn 20 to 22 hours a day and removed for meals, so younger kids might have trouble hanging on to them. Patients get a new device every two weeks, and the treatment can be pricier than braces, although it takes about the same amount of time [source: Invisalign].