Extra-oral Traction and Functional Appliances—A Cephalometric Comparison

Abstract

The importance of correcting Angle's Class II molar relationships during orthodontic treatment is discussed and two methods of achieving this correction are described. The literature is reviewed and an investigation designed to compare the modes of action of extra-oral traction and functional appliances is described. The base line for cephalometric measurement is taken as S-N with a perpendicular axis constructed at S in order to minimize errors due to growth occurring during the investigation period. Results suggest that neither appliance has significant effects on the horizontal growth of the dental bases, but that the clinical effect of molar relationship correction is substantially due to dento-alveolar changes.