There are reasons other than esthetics alone that make it a good idea to straighten your teeth. If your teeth are crowded or overlapped, this can actually raise your risk of developing decay and gum disease.
It’s simply more difficult to brush and floss teeth that are not straight and even. If you are not cleaning your teeth properly, plaque can more easily build up below the gum line. Even gaps between your teeth can be problematic if there is a tendency for food to get trapped between your teeth.