Effect of maxillary extraoral anchorage on the maxillofacial complex : Differences in palatal plane inclination

Abstract

We investigated the effect of an extraoral anchorage appliance by the strain gauge method using two dry human skulls of Hellman's developmental stage VA with different palatal plane angles. We set an edgewise appliance and palatal bar on the skull and measured the strain when a 3kg force was applied to short, medium and long outer bows of a race bow headgear. The strain on the sutures was greater than the strain on the bone around the sutures. In the skull with a low palatal plane angle, even downward traction by the headgear produced backward and upward distortion of the maxilla with counter-clockwise rotation.