術前矯正治療における下顎骨および下顎頭の位置変化について

Abstract

The purpose of this study was to examine the cephalometric changes of mandibular and condylar position during preoperative orthodontic treatment. The materials in this study were lateral cephalograms and lateral radiographs of the temporomandibular joint from18cases of mandibular protrusion undergoing orthognathic surgery. These were taken at the initial (A) and the end (B) of the preoperative orthodontic treatment. Linear and angular measurments were made and analyzed statistically, and superimpositions of the condyle in the condylar fossa were also performed.The results were as follows:1. During preoperative orthodontic treatment, the Menton moved anterosuperiorly or anteroinferiorly or posteroinferiorly. The SN-Mandibular plane angle increased in some cases, but decreased in other cases.2. Condylar positions also changed in many cases, but the extent of the change was much less thanthat of Menton. Superimpositions of the condyle in the condylar fossa showed complicated changes which consisted of anteroposterior and superoinferior movement combined with rotation of the condyle.3. There was a statistically significant correlation in the rotation of the mandible and condyle. But here was no statistically significant difference in the horizontal and vertical movements of the Menton and condyle.These results strongly suggest that the mandibular position has changed in preoperative orthodontic treatment. Therefore, it is worthwile to examine the changes of the mandibular position including condyle prior to determination of external bone fragments during the surgical procedures of sagittal split osteotomy of the ascending ramus and screw fixation.