Cha Jihun, Park Kyuwon, Ryu Jaeyoung, Jung Seunggon, Park Hong-Ju, Oh Hee-Kyun, Kook Min-Suk
Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Science Research Institute, Chonnam National University, 42, Jebong-Ro, Dong-Gu, Gwangju, 61469, Republic of Korea.
Maxillofac Plast Reconstr Surg. 2024 Sep 2;46(1):32. doi: 10.1186/s40902-024-00442-9.
Relapses following orthognathic surgery have been reported to exceed 2% to 50%, depending on multiple factors. This study aimed to analyze the stability after orthognathic surgery in patients with mandibular ramus height asymmetry through 3D reconstruction using Cone-beam CT.
This retrospective cohort study investigated patients who underwent mandibular setback surgery using bilateral sagittal split ramus osteotomy. Three-dimensional CT scans were taken at three different time points. Evaluation of the postoperative stability involved measuring changes in the x, y, and z axes as well as roll and yaw rotations of the mandible at specific landmarks (B point, mental foramen) on 3D CT scans obtained immediately after surgery and 6-12 months postoperatively. They were categorized into four groups based on bilateral mandibular height asymmetry through Asymmetry index (AI). The one-way ANOVA was implemented to compare the intergroup differences and Tukey's post hoc test was employed. Additionally, the Pearson correlation coefficient was also calculated.
A total of 24 patients were included in this study. The corresponding AI, representing the degree of asymmetry in both mandibles, were calculated as Group 1 was 1.25 ± 0.64%, Group 2 was 2.89 ± 0.47%, Group 3 was 5.03 ± 0.51%, and Group 4 was 9.40 ± 1.99%. The x-axis change in Group 4 was significantly larger at 1.71 mm compared to Group 1 at 0.64 mm. The mandibular roll, Group 4 showed a statistically significant increase at 1.33° compared to Group 1 at 0.35°. And there was a significant positive correlation observed between x-axis change and AI (p = 0.019), as well as between mandibular roll and AI (p = 0.025).
After orthognathic surgery, stability was influenced by numerous factors, with the findings of this study suggesting that the degree of ramus height asymmetry in the mandible can be considered one contributing factor.
据报道，正颌手术后的复发率在2%至50%之间，具体取决于多种因素。本研究旨在通过锥形束CT三维重建分析下颌升支高度不对称患者正颌手术后的稳定性。
这项回顾性队列研究调查了接受双侧矢状劈开下颌升支截骨术进行下颌后缩手术的患者。在三个不同时间点进行三维CT扫描。术后稳定性评估包括在手术后立即和术后6至12个月获得的三维CT扫描上，测量特定标志点（B点、颏孔）处下颌骨在x、y和z轴上的变化以及滚动和偏航旋转。根据不对称指数（AI）将双侧下颌高度不对称患者分为四组。采用单因素方差分析比较组间差异，并采用Tukey事后检验。此外，还计算了Pearson相关系数。
本研究共纳入24例患者。计算出的代表双侧下颌骨不对称程度的相应AI，第1组为1.25±0.64%，第2组为2.89±0.47%，第3组为5.03±0.51%，第4组为9.40±1.99%。第4组的x轴变化为1.71mm，明显大于第1组的0.64mm。下颌滚动方面，第4组为1.33°，与第1组的0.35°相比有统计学显著增加。并且在x轴变化与AI之间（p = 0.019）以及下颌滚动与AI之间（p = 0.025）观察到显著正相关。
正颌手术后，稳定性受多种因素影响，本研究结果表明下颌升支高度不对称程度可被视为一个影响因素。
