Antero-Posterior Movement of the Maxillae with a Modified Sutural Expansion Device

Abstract

It was the purpose of this study to discover if anteroposterior movement of the maxillary bones was possible. Seven cats were used as the experimental animals. An expansion device which produced a diagonal force from one maxillary cuspid to the opposite molar was inserted in five of the animals. Two animals were used as controls. The effects of the lateral and antero-posterior components of the force were studied by means of before and after models, oriented occlusal radiographs, and histologic sections. Antero-posterior movement did occur. The anterior movement was more evident than the posterior movement due to the response evoked in the premaxillary-maxillary and the maxillary-palatine sutures. The sutures which were compressed showed very little response when viewed in horizontal histologic sections as compared to the sutures which were under tension. The sutures under tension showed marked osteophytic production which generally grew parallel to the line of force application. This difference in response allowed one side to remain as an anchorage unit while the opposite side moved anteriorly. The lateral increase in width appeared to be stable. In one animal the force was removed for thirty six days prior to sacrifice. In this animal the stability of the antero-posterior movement was questionable.