It’s not just straightening teeth any more. Orthodontists can move teeth of course, but they may also modify facial growth. Correcting adult malocclusion can often save teeth usually lost to periodontal disease.  Braces don’t have to be all metal any more.  Clear or ceramic brackets can be almost invisible. New techniques like Invisalign can correct minimal to moderate malocclusion with tooth positioners and no wires at all.