The straight-wire concept.
D003724:Dental Arch / Q000033:anatomy & histology; D049673:History, 20th Century; D009967:Orthodontic Appliances / Q000266:history*; D013314:Stress, Mechanical; D014070:Tooth / Q000033:anatomy & histology; D014087:Tooth Movement Techniques / Q000266:history / Q000379:methods