下颌前突畸形患者上颌骨及髁突虚拟位置与术后现实位置的比较

Comparison of the virtual surgical planning position of maxilla and condyle with the postoperative real position in patients with mandibular protrusion

目的:对比数字化正颌外科手术方案中上颌骨及髁突的虚拟位置与术后现实位置的差别,探究术前虚拟设计在术中实现的程度。方法:选择2022年1—12月于北京大学口腔医院采用数字化正颌手术方案行双颌手术的骨性Ⅲ类下颌前突畸形患者36例,收集患者术前数字化正颌手术方案(T_(0))和术后1周CT数据(T_(1)),使用CCMF Plan软件对术后CT数据进行三维建模并替换术后模型中的牙列数据,将颅骨解剖结构与术前虚拟设计模型进行匹配,选取髁突及上颌骨的解剖标志点及其连线,对比标志点在三维方向上的坐标变化以及标志点连线与参考平面的角度变化,分析术后髁突及上颌骨位置相对虚拟设计中的位置偏差。结果:术后上颌骨实际位置与虚拟设计位置在水平向及垂直向的偏差为1 mm左右,前后向偏差约为1.5 mm。术后双侧髁突与虚拟设计位置相比,大多发生向前、向外、向下的移动(平均距离分别为0.15 mm、1.54 mm、2.19 mm)及向前、向外、向上的旋转(平均角度分别为4.32°、1.02°、0.86°)。结论:采用3D打印咬合导板辅助可较好实现数字化手术方案的虚拟设计,但与术后颌骨的实际位置存在一定误差,可能与虚拟设计中下颌旋转轴有关,提示有必要采用患者个性化髁突旋转轴进行数字化正颌手术方案的规划,并采用髁突定位装置来提高手术操作的精确性。

Objective:To compare the difference between virtual surgical planning(VSP)position and postoperative real position of maxilla and condyle,and to explore the degree of intraoperative realization of VSP after orthognathic surgery.Methods:In this study,36 patients with mandibular protrusion deformity from January 2022 to December 2022 were included.All the patients had been done bilateral sagittal split ramus osteotomy(SSRO)combined with Le FortⅠosteotomy under guidance of VSP.The VSP data(T_(0))and 1-week postoperative CT(T_(1))were collected,the 3D model of postoperative CT was established and segmented into upper and lower jaws in CCMF Plan software.At the same time,accor-ding to the morphology of palatal folds,the virtual design was registered with the postoperative model,and the unclear maxillary dentition in the postoperative model was replaced.Then the postoperative model was matched with VSP model by registration of upper skull anatomy that was not affected by the operation.The three-dimensional reference plane and coordinate system were established.Selecting anatomical landmarks and their connections of condyle and maxilla for the measurement,we compared the coordinate changes of marker points in three directions,and the angle changes between the line connecting the marker points and the reference plane to analyze the positional deviation and the angle deviation of the postoperative condyle and maxilla compared to VSP.Results:The postoperative real position of the maxilla deviates from the VSP by nearly 1 mm in the horizontal and vertical directions,and the anteroposterior deviation was about 1.5 mm.In addition,most patients had a certain degree of counterclockwise rotation of the maxilla after surgery.Most of the bilateral condyle moved forward,outward and downward(the average distance deviation was 0.15 mm,1.54 mm,2.19 mm,respectively),and rotated forward,outward and upward(the average degree deviation was 4.32°,1.02°,0.86°,respectively)compared with the VSP.Conclusion:VSP can be mostly achieved by assistance of 3D printed occlusal plates,but there are certain deviations in the postoperative real position of maxilla and condyle compared with VSP,which may be related to the rotation axis of the mandible in the VSP.It is necessary to use patient personalized condylar rotation axis for VSP,and apply condylar positioning device to further improve surgical accuracy.