title: The systems of directional force.
mesh_terms: D001696:Biomechanical Phenomena; D003724:Dental Arch / Q000502:physiology; D005115:Extraoral Traction Appliances; D006801:Humans; D008310:Malocclusion / Q000628:therapy; D008334:Mandible / Q000502:physiology; D008437:Maxilla / Q000502:physiology; D009967:Orthodontic Appliances; D014087:Tooth Movement Techniques / Q000379:methods*