舌骨位を判定基準とした無歯顎者下顎位安定度の予知的診断法

抄録

The purpose of this study was to establish a method for predicting the postoperative stability of the mandibular position after treatment of an edentulous patient before treatment. The distance between the apex on Gothic arch tracing (GA) and the tapping point (TP) of 21 Japanese female edentulous patients who had obtained good oral conditions by using dentures during treatment was measured after treatment. The 21 patients were classified into group A (15 patients) whose distances between GA and TP were less than 2.0 mm and their mandibular positions were stable, and group B (6 patients) whose distances between GA and TP were equal to or more than 2.0mm and their mandibular positions were unstable.
The postoperative lateral cephalometric radiographs of the 21 patients were analyzed in view of the hyoid bone position in reference to a reference plane (called pterygoid vertical plane) fixed to the base of the cranium. The hyoid bone positions of group B patients were significantly anterior, 9.9 mm in average (p=0.0023), to those of group A patients. On the other hand, the changes of the hyoid bone positions from preoperative to postoperative were little in both groups. Based on the above, it was suggested that the preoperative measurement of the hyoid bone position on lateral cephalometric radiograph was effective for predicting the postoperative stability of the mandibular position in edentulous patient.