辅助髁突定位改良型咬合导板的设计与制作

Design and Manufacture of An Improved Guiding Splint for Condylar Positioning

目的:运用计算机辅助设计和制作一种在下颌矢状截骨手术中准确控制髁状突位置的咬合-定位一体化装置,并通过实验验证其准确性。方法:随机选取在南昌大学附属口腔医院口腔颌面外科就诊,完成术前正畸治疗拟行正颌手术的患者10例,共20侧髁突。行头颅及石膏模型CT扫描,使用Mimics 17.0软件生成上、下颌三维模型,按手术计划完成虚拟截骨及骨块移动,建立新的上下颌骨空间关系,将髁突的位置信息记录为虚拟组数据。使用Freeform12.0软件设计咬合导板和下颌近心端定位导板,并通过连接杆将咬合导板与定位导板实现一体化。使用3D打印机分别打印一体化定位装置、下颌骨近端骨块、远端骨块等实物模型部件,利用一体化定位装置将实物部件连为一体后行CT扫描,将所得Dicom数据作为模型组数据导入到Mimics 17.0软件中。测量虚拟组和模型组中3个髁突标志点的线性差异及坐标差异,评价髁突位置及空间姿态的变化,统计学分析使用均方根偏差(RMSD)分析。结果:3固位臂设计对下颌近心端具备良好的固位效果,统计学分析虚拟手术组和模型手术组的髁突位置信息显示了非常好的一致性,最大位置RMSD差异为0.738mm,最大姿态角度RSMD差异为1.1°。结论:计算机辅助设计与制作的咬合-定位一体化导板在体外模型实验中能够对髁状突进行精确定位,且设计、制作简单,有望作为一种正颌手术中髁突定位装置的选择。

Objective：To describe the design and manufacture of a novel condylar positioning device with computer-aided design in sagittal split ramus osteotomy,and to verify the accuracy by model test.Methods：The sample included 10 patients with a total 20 condyles.The patients had completed preoperative orthodontic treatments and were undergoing orthognathic surgeries.CT data containing patient＇s jaw and occlusion information were imported into Mimics 17.0 software.The mandible and midface were reconstructed,and were completed with the virtual SSRO,Lefort I osteotomy and bone movements,to obtain a new upper and lower jaw position.Freeform 12.0 software was used to design the guiding splint and proximal segment positioning guide.They were connected with a cylinder.Integrated condylar positioning device,proximal segment,and distal segment were 3D printed.The condylar positioning devices were used to connect the proximal segment models and distal segment models.The segments were joined together and went through a CT scan.CT data were imported into Mimics 17.0 software,the linear differences and coordinate differences of three condylar landmarks in the virtual group and the model group were measured.Statistical analyses were performed using RMSD.Results：Excellent consistency was proved with largest positional RMSD of 0.738 mm and largest postural angular RSMD discrepancy of 1.1°.Conclusion：This condylar positioning device with computer-aided design can accurately locate the condyles in in vitro experiment,which might be used as an alternative method to obtain the correct position of the condyle in orthognathic surgery.