骨格性下顎前突症における顎矯正手術前後の咽頭気道形態の変化―下顎骨後退術と上下顎移動術の比較―

Abstract

The purpose of this study was to compare the changes in pharyngeal airway space after mandibular setback surgery with those after two-jaw surgery in skeletal Class III patients. Subjects were selected from consecutive patients with Class III patients treated with orthognathic surgery, and divided into two groups: 13 patients received mandibular setback surgery (MS group) and 8 patients received two-jaw surgery (TW group). First, jaw relationship, head posture, tongue positionand pharyngeal airway space were compared between two lateral cephalograms takenbefore surgery (TO) and one or more year after surgery (T1) in each group. Then, the surgical changes occuring from TO to T1 (T1-TO) were calculated and statistically compared between the two groups. As a result, jaw relationships were improved significantly in both groups after the surgery since ANB increased from TO to T1 in both groups, 5.3 degrees in the MS group and 7.1 degrees in the TW group, respectively. The head posture and tongue position did not appear to change significantly due to the surgical intervention between the two groups. The palatalpharyngeal space increased significantly in the TW group, while there was no significant post-operative difference in the MS group. On the contrary, the superior posterior pharyngeal space and middle pharyngeal space decreased significantlyin the MS group, while there was no significant post-operative difference in theTW group. All these changes showed significant differences between the two groups. On the other hand, the epiglottic pharyngeal space decreased in both groups, and the ratio was smaller in the TW group than in the MS group. In conclusion, our results indicated that two-jaw surgery actually seems to improve the jaw relationship compared to mandibular setback surgery, while the pharyngeal airway space behind the soft palate is maintained and middle airway space except for thoseis not narrower than in mandibular setback surgery. Also, the results suggest wehave to take into consideration that the pre-operative pharyngeal airway, as well as facial pattern and stability after surgery, affects the post-surgical course in orthognathic surgery of skeletal Class III patients though narrowing of thepharyngeal airway space did not cause breathing disorders.