In the old days (and still now for most North American orthodontist specialists) it was all about fitting teeth into the space provided by the underdeveloped jaw bones. So teeth were removed, strong forces were applied and the remaining teeth were lined up. This created a multitude of problems. As faces and teeth age the teeth came out of alignment, becoming crowded, jaw joints were also crowded adding to TMJ problems, and because the faces were constricted during the process, the airways were constricted leading to reduced oxygen intake. The leading edge in orthodontic treatment is now to promote facial development, reducing the need to remove teeth. Gentle forces promote growth and help in obtaining more genetic potential. Less teeth need to be removed to make things fit, joints are healthier and the airway is wider.