Abstract
The purpose of this study was to compare the dimensional change in the upper airway of prognathic patients who underwent either sagittal split ramus osteotomy (SSRO) surgery only or a combination of Le Fort I osteotomy and SSRO surgery. The sample consisted of 65 patients who were diagnosed as having skeletal mandibular prognathism. They were divided into two groups: 32 patients who underwent mandibular setback surgery using SSRO (SSRO group) and 33 patients who underwent two-jaw surgery (i.e., Le Fort I osteotomy plus SSRO; two-jaw group). To compare the jaw relationship, the position of the hyoid bone and upper-airway dimensions using sets of three lateral cephalometric radiographs that were taken before surgery (T0), at three months after surgery (T1) and two or more years after surgery (T2) were examined in each group. As a result, the middle and inferior upper-airway dimensions became narrower after surgery and the middle upper-airway dimensions recovered after a few years in the SSRO group and two-jaw group. In the SSRO group, a significant positive correlation was found between the amount of mandibular set-back and the middle or inferior upper airway from T0 to T1, and T0 to T2. In the two-jaw group, a significant positive correlation was found between the amount of mandibular set-back and the middle or inferior upper airway only from T0 to T1. In both groups, the position of the hyoid bone was changed to the infero-posterior position from T0 to T1. After that, the hyoid bone in the SSRO group changed to a more superior position. However, the result was different in the two-jaw group because the position of the hyoid bone returned to the same position as before surgery. In conclusion, when orthognathic surgery is performed, it is suggested that the surgical method influences the upper-airway dimension between those patients treated with only SSRO and those with two-jaw surgery.
