目的: 基于下颌运动轨迹建立正颌手术下颌骨髁突位置的术前规划和术中定位技术流程，并对其定位准确性进行评价。方法: 通过大视野锥形束计算机体层摄影术(cone beam computed tomography, CBCT)和口内扫描分别获得面部骨组织和牙齿的三维数据，采用下颌运动记录仪记录患者下颌生理状态下各方向运动时的下颌运动轨迹。使用IVSPlan l.0.25软件，通过数据分割、三维重建得到上、下颌骨的三维模型，通过标志点配准将牙列数据与颌骨数据融合，将下颌运动记录仪得到的数据转化为下颌骨相对于上颌骨的矩阵变换方程组，通过下颌骨三维数据的矩阵变换得到不同时刻下颌骨髁突的坐标位置，并通过软件可视化呈现其三维运动轨迹。由一名具有颞下颌关节病诊治和正颌外科手术双专业背景的高年资口腔颌面外科医师在可视化界面上筛选合适的下颌骨髁突位置作为近心骨段的术后位置，常规进行正颌外科设计，基于咬合关系和面型设计远心骨段位置，将近、远心骨段数据融合得到术后下颌骨形态，通过3D打印得到实体模型。在实体模型上预成型钛板、打孔，设计下颌骨髁突定位导板。手术中，通过下颌骨髁突定位导板和预成型钛板引导包含下颌骨髁突的近心骨段就位于术前设计位置。通过10例骨性Ⅱ类牙颌面畸形患者验证该流程在双侧下颌升支矢状劈开截骨术(sagittal split ramus osteotomy, SSRO)中定位下颌骨髁突的准确性。误差的计算方法为术前设计与术后2周CBCT实际下颌骨髁突表面距离的均方根(root mean square, RMS)。结果: 术前设计下颌骨髁突位置与术后2周的实际位置相比，下颌骨髁突表面平均距离的RMS为(1.59±0.36) mm，95%CI：1.35~1.70 mm，小于2 mm的专家共识建议值(P < 0.05)。结论: 下颌运动轨迹对正颌外科手术设计中确定包含下颌骨髁突的近心骨段位置可能具有指导作用，使用下颌骨髁突定位装置和预成型钛板术中引导下颌骨髁突就位的精度可以满足临床需求。

Objective: To establish and assess the precision of pre-surgical condyle position planning using mandibular movement trajectory data for orthognathic surgery. Methods: Skull data from large-field cone beam computed tomography (CBCT) and dental oral scan data were imported into IVSPlan 1.0.25 software for 3D reconstruction and fusion, creating 3D models of the maxilla and mandible. Trajectory data of mandibular movement were collected using a mandibular motion recorder, and the data were integrated with the jaw models within the software. Subsequently, three-dimensional trajectories of the condyle were obtained through matrix transformations, rendering them visually accessible. A senior oral and maxillofacial surgeon with experience in both diagnosis and treatment of temporomandibular joint disease and orthognathic surgery selected the appropriate condyle position using the condyle movement trajectory interface. During surgical design, the mobile mandibular proximal segment was positioned accordingly. Routine orthognathic surgical planning was completed by determining the location of the mandibular distal segment, which was based on occlusal relationships with maxilla and facial aesthetics. A virtual mandible model was created by integrating data from the proximal and distal segment bone. Subsequently, a solid model was generated through rapid prototyping. The titanium plate was pre-shaped on the mandibular model, and the screw hole positions were determined to design a condylar positioning guide device. In accordance with the surgical plan, orthognathic surgery was performed, involving mandibular bilateral sagittal split ramus osteotomy (SSRO). The distal segment of the mandible was correctly aligned intermaxillary, while the proximal bone segment was positioned using the condylar positioning guide device and the pre-shaped titanium plate. The accuracy of this procedure was assessed in a study involving 10 patients with skeletal class Ⅱ malocclusion. Preoperative condyle location planning and intraoperative positioning were executed using the aforementioned techniques. CBCT data were collected both before the surgery and 2 weeks after the procedure, and the root mean square (RMS) distance between the preope-rative design position and the actual postoperative condyle position was analyzed. Results: The RMS of the condyle surface distance measured was (1.59±0.36) mm (95%CI: 1.35-1.70 mm). This value was found to be significantly less than 2 mm threshold recommended by the expert consensus (P < 0.05). Conclusion: The mandibular trajectory may play a guiding role in determining the position of the mandibular proximal segment including the condyle in the orthognathic surgery. Through the use of a condylar positioning guide device and pre-shaped titanium plates, the condyle positioning can be personalized and customized with clinically acceptable accuracy.