Le Fort Ⅰ型截骨术上抬上颌骨与下颌骨自动旋转中心的相关性研究

The Inter-relationship between mandibular rotation and maxillary Le Fort Ⅰ osteotomies

目的:探讨Le Fort I型截骨术上抬上颌骨后,下颌骨自动旋转中心位置变化与上颌骨上抬距离的关系。方法:选取10例患者,均为上颌骨垂直向发育过度导致开唇露齿和下颌骨后下旋转,而下颌骨发育正常,采用单纯LeFortI型截骨术上抬上颌骨,矫正其牙颌面畸形。拍摄术前、术后头颅定位侧位片,利用Reuleaux法测量实际的下颌骨旋转中心位置,应用SPSS10.0软件包对ANS、PNS上抬量与下颌骨自动旋转中心位置进行Spearman秩相关分析。结果:下颌骨平均自动旋转中心位于蝶鞍点下方49.350mm、后方17.100mm处。髁突中心位于蝶鞍点下方24.000mm、后方11.950mm处。下颌骨自动旋转中心垂直向位置与ANS点的上抬量高度相关(P=0.008)。下颌骨自动旋转中心垂直向位置与PNS点的上抬量高度相关(P=0.045)。结论:下颌骨旋转中心位于髁突外。下颌骨自动旋转中心与上颌骨上抬幅度高度相关。

PURPOSE： To locate the instantaneous rotation center of mandible autorotation during maxillary surgical impaction,and find the interrelation between the magnitude of maxillary surgical impaction and the rotation center of mandible autorotation. METHODS： Ten patients underwent maxillary Le Fort Ⅰ impaction without concomitant major mandibular ramus split osteotomies were included. The preoperative and postoperative lateral cephalograms were used to evaluate the surgical changes and locate the center of rotation of mandibular autorotation with Reuleaux method. The data were analyzed by Spearman rank test with SPSS12.0 software package. RESULTS： The center of rotation was located, in average, 17.100mm below and 49.350mm behind the sella point in these ten patients. The correlation analysis demonstrated a positive correlation between the magnitude of superior displacement of the ANS point and the vertical position of the rotation center of mandible （P=0.008）.The similar positive correlation was also presented in the magnitude of superior impaction of the PNS and the vertical position of the rotation center of mandible （P=0.045）. CONCLUSION： The rotation center in these ten cases located outside the condyle head. The radiographic condylar center of the mandible, as we chose for the presurgical predictions, may not be the most representative rotary axis of mandibular autorotation during the surgical maxillary impaction. The magnitude impaction of the maxilla was highly and positively correlated to the vertical position of the rotation center of the mandible.