基于CT的三维正颌手术仿真模拟平台的建立

目的:建立基于CT的三维正颌手术仿真模拟平台,通过计算机定性定量模拟畸形矫治,并精确设计手术方案。方法:取医学实验用成年男性尸体,进行头颅螺旋CT扫描并完成三维图像重建;解读标准DICOM3.OCT数据库,采用VisualC 6.0语言、VTK工具包在PC机上编制出三维显示、交互式操作模拟手术仿真平台。结果:实现了在颌骨三维模型上以人机交互方式任意切割并按要求定量移动或旋转骨的目标,可模拟畸形矫治过程。结论:借助专用软件和计算机图形学方法,基于CT的三维手术仿真模拟平台,使外科医生能应用逼真的三维可视图像进行诊断分析、术前模拟预测和术后评价,从而使正颌外科手术更为精确。     

骨性Ⅲ类错(牙合)正颌术后颊部宽度变化的三维研究

目的 探讨骨性Ⅲ类错(牙合)患者正颌术后颊部宽度变化的规律.方法 20例完成正颌手术的骨性Ⅲ类错(牙合)患者,男性9例,女性11例,平均年龄(25.06±5.33)岁,其中9例接受双侧下颌升支矢状劈开截骨(Bilateral sagittal split ramus osteotomy,BSSRO)后退术,11例接受Lefort-Ⅰ型截前移骨术和BSSRO后退术,分别在术前2周(T1)、术后6个月(T2)进行面部激光扫描检查,手术前后软组织面型的三维图像在同一坐标系中完成测量,分析颊部宽度的变化.结果 在经过外眦连线中点的冠状截面上,20例患者术后单侧颊部软组织宽度增加(3.58±2.21) mm,不同性别之间无显著性差异;下颌后退组单侧颊部增宽(1.74±0.76) mm,双颌手术组单侧颊部增宽(5.00±1.86) mm,两组之间存在显著性差异(P=0.001).结论 骨性Ⅲ类错(牙合)接受单纯下颌后退或者双颌手术后,颊部宽度均有增加的趋势.     

计算机辅助正颌外科的研究现状

计算机与医学影像技术的快速发展加速了生物医学工程的发展,计算机辅助正颌外科也成为了目前的研究热点。计算机技术贯穿至术前资料的采集与分析、手术计划、手术效果预测和虚拟手术的现实转移整个过程中,具有传统方法无法比拟的优点,是今后正颌外科的发展方向。本文将围绕以上各环节的研究进展作一综述。     

三维摄影技术结合锥形束CT评估颜面部不对称患者正颌手术前后的软硬组织变化

目的探讨骨性Ⅲ类颜面部不对称畸形的患者正畸正颌联合治疗前后,面部软硬组织各部分对称性的改变。方法选择20例来我院进行正畸正颌联合治疗的骨性Ⅲ类偏颌患者,在术前、术后拍摄的锥形束计算机断层扫描(cone-beam computed tomography scans,CBCT)与三维照片(three-dimensional facial scanning images,3dMD)上描记25个标志点,对同一标志点术前术后的不对称性进行统计分析。结果软组织中,上唇缘点、下唇缘点、左右口角点、下颌角点、颏前点、颏下点的不对称性差异有统计学意义。硬组织中,B点、颧牙槽嵴点、颏孔点、下颌角点、颏前点、颏下点的不对称性差异有统计学差异。结论正畸正颌联合治疗后的患者,其唇部、颏部软组织不对称性得到巨大改善,下颌硬组织不对称性有较大改变,而鼻部软组织无明显改变。     

正颌外科三维立体可视化模拟手术研究

目的：建立基于CT图像数据的计算机辅助三维立体手术模拟系统，为了术前进行精确设计手术方案及达到术后良好效果提供真实可靠依据。方法：应用医学可视化技术和Visual C^**编程语言开发出立体结构三维重建和手术模拟软件，建立以CT数据为信息源的计算机正颌外科立体可视化手术仿真模拟系统，可模拟各种正颌外科手术移动骨质过程，并且以动态动画形式演示，可从任意角度进行观察。结果：该系统建立了颅颌面畸形立体结构模型，以动态形式成功演示了正颌外科截骨移动手术仿真模拟，手术过程真实逼真，立体可视化效果好，应用普通播放软件即可在计算机屏幕上播放模拟正颌外科手术过程，并可预测手术后上下颌咬合状态及手术效果。结论：正颌外科三维立体可视化模拟手术系统的建立，为正颌外科截骨矫治牙颌面畸形术前手术方案制定提供实用有效的技术手段和全心的科学方法，改变仅凭主观经验诊断畸形和设计手术方案的传统模式，可在计算机屏幕前制定手术方案进行医患交流，共同协商，提高了正颌外科手术安全性、精确性和矫治效果。     

正颌手术对颌面硬组织对称性改变的三维评估

目的 通过锥形束CT（cone beam computed tomography,CBCT）研究正颌手术对成人骨性Ⅲ类错牙合伴颜面部不对称患者治疗的疗效。方法 选择正畸临床成人骨性Ⅲ类错牙合伴颜面部不对称患者20例,20例患者均采用正畸-正颌联合治疗的方法,在正畸前（T0）和正颌手术后6个月（T1）后使用CBCT对患者进行三维扫描获得颅面部DICOM数据,采用Dolphin 11.0对颌骨进行三维重建,选择描述颌骨骨性结构特征的20个点进行描记,测量分析20个变量。结果 20例颜面部不对称患者,正颌手术改善上颌骨下部水平向及矢状向的不对称性,双侧下颌体的长度及下颌支的倾斜度得到纠正。结论 正颌手术能有效改善成人颜面部不对称,对成人骨性Ⅲ类错牙合伴颜面部不对称患者的改善主要表现在上颌骨下部水平向及矢状向的对称性改善,以及下颌体长度不协调的纠正,正颌手术前三维测量对正颌治疗方案的制定及预后的判断至关重要。     

骨性Ⅲ类错牙合患者正畸正颌联合治疗前后面部软组织变化的研究

目的探讨骨性Ⅲ类错牙合患者正畸正颌联合治疗前后面部软组织变化的特征。方法选择在江苏省口腔医院正畸科就诊的14例骨性Ⅲ类错牙合畸形的患者为研究对象,分别于正畸正颌联合治疗前、后拍摄3dMD,利用3dMD vultus软件对颌面部软组织进行重建,然后选取面部软组织有代表性的17个三维标志点并测量线距和角度,比较骨性Ⅲ类错牙合患者正畸正颌联合治疗前后的差异。结果面凸角、鼻唇角、颏唇角、上唇长度,鼻翼宽度及鼻基底宽度有统计学差异,P<0.05。结论①3dMD提供了三维测量软组织的一种方法。②骨性Ⅲ类错牙合患者正畸正颌联合治疗前后面型改善。     

计算机模拟正颌外科手术及疗效预测的研究

本文报告作者在个人计算机上开发的一个交互作用系统，用于模拟设计正颌外科手术及预测术后治疗效果。经临床应用取得了满意可靠的结果。     

唇腭裂患者正颌术后上颌骨短期稳定性的三维分析

目的:建立一种可同时反映上颌骨位置及姿势的三维测量方法,对唇腭裂患者上颌骨正颌术后的短期稳定性进行三维评估.方法:选取因唇腭裂继发上颌骨发育不足而行正颌手术的25例患者,按照患侧分为左侧唇腭裂组10例、右侧唇腭裂组8例、双侧唇腭裂组7例;收集术前6周(T0)、术后4天(T1)、术后3个月(T2)、6个月(T3)的全头颅螺旋CT资料,利用计算机辅助设计软件ProPlan建立三维坐标系,设定22个描述上颌骨空间位置的指标,并定义3个姿势角∠ PP-CP、∠RP-CP、∠YP-CP,分别表示上颌骨在空间内俯仰、侧滚、摆尾.利用SPSS16.0软件包对T2、T3时的测量结果进行配对t检验.结果:成功建立了较为完整反映上颌骨空间位置及姿势的测量方法.在垂直向上,颌骨前部牙骨段向上的总体复发率为7.46％;在矢状向上,各组复发率分别为30.95％、8.01％和34.76％,无显著差异;在水平向上,单侧完全性唇腭裂组均出现整体向健侧平移,且前部偏向健侧、而后部偏向患侧偏转的复发趋势.结论:腭裂患者正颌术后上颌骨在三维方向内存在复发趋势,本研究建立的三维测量比二维研究能更有效地从平移和旋转的角度进行评估.     

Three-dimensional facial morphometric assessment of soft tissue changes after orthognathic surgery

OBJECTIVE: In this study, a 3-dimensional system with landmark representation of the soft tissue facial surface was applied for the evaluation of facial changes occurring after orthognathic surgery in 5 patients. StUDY DESIGN: Standardized facial landmark acquisitions were performed before and 1 year after surgery (combined maxillary Le Fort I and sagittal mandibular osteotomies). The 3-dimensional coordinates of 22 facial soft tissue points were collected on each subject through use of a computerized noninvasive method and used to calculate a set of selected parameters. RESULTS: Three-dimensional soft tissue analysis of patients was in general agreement with the type of surgery performed, with volumetric contraction of the lower facial third and expansion of the middle facial third. Moreover, negative effects of surgery were quantified (eg, an increase in alar base dimensions); the global asymmetry of facial soft tissues was increased by intervention, but asymmetry in the lower facial third was reduced. CONCLUSIONS: The method used in this study proved useful as a complementary diagnostic aid, enabling quantitative evaluation of the final soft tissue results of surgery, which were proportional to those expected on the basis of the type of treatment and skeletal data.     

Visualizing three-dimensional facial soft tissue changes following orthognathic surgery

Laser scanning can be used to visualize the face in three dimensions. These scans can then be processed to enable assessment of facial changes. The aim of this single-centre, prospective, longitudinal, cohort study was to investigate whether four different visualization methods correctly represented facial changes occurring as a result of orthognathic surgery. Twenty-six consecutive orthognathic patients (13 female mandibular advancement and 13 male bimaxillary Class III) were included as well as a control group of 12 non-growing adults (6 males and 6 females). Pre- and post-operative facial laser scans were superimposed and four different visualization methods applied: correspondences with sensitivity to movement, normals, radial, and closest point. A group of 10 'blinded' observers determined the surgical procedure (if any) that had been performed by applying a specific colour scale to each facial image. The sensitivities and specificities for each visualization method applied to each subject group were determined. The intraobserver repeatability was investigated using Cohen's kappa (k). The radial method was found to be superior for identifying mandibular advancement patients (sensitivity/specificity 58.5/92.4 per cent), the normals method for visualization of bimaxillary Class III cases (26.2/99.6 per cent), while the control group was best represented using the closest point (60.0/80.8 per cent). Overall, intraobserver repeatability was good (k = 0.61). A good level of repeatability was demonstrated in the separate subject groups (mandibular advancement 0.70, bimaxillary Class III 0.70, and controls 0.62). There was no significant difference in the abilities of the four visualization methods to represent facial changes. Each method allowed correct identification of different proportions of the subject groups.     

Three-dimensional analysis of facial morphology before and after orthognathic surgery

A method for three-dimensional analysis of the facial hard- and soft-tissue morphologies is described. The soft-tissue analysis consisted of calculating three-dimensional values of reference points on the face by perspective transformation of their values in two pairs of photographs, taken simultaneously, from the right and left sides of the face. The shape of the mandible was analyzed three-dimensionally by the simultaneously taken frontal and lateral cephalograms. The hard- and soft-tissue changes were analyzed with the method in 28 patients in whom mandibular prognathism had been corrected by orthognathic surgery. The magnitude of the surgically-produced soft tissue volumetric changes in the anterior mandibular region was proportional to the posterior movement of the mandible. Asymmetry of the face also improved in response to correction of lateral deviation of the mandible and a close correlation between the directional indices of asymmetry of the hard and soft tissues was observed. Thus, the method was found to be quite useful for the analysis of facial morphology in jaw deformity.     

Soft tissue response and facial symmetry after orthognathic surgery

ObjectiveIn orthognathic surgery aesthetic issues and facial symmetry are vital parameters in surgical planning. Aim of this investigation was to document and analyze the results of orthognathic surgery on the base of a three-dimensional photogrammetric assessment, to assess the soft tissue response related to the skeletal shift and the alterations in facial symmetry after orthognathic surgery.Patients and methodsIn this prospective clinical trial from January 2010 to June 2011, 104 patients were examined who underwent orthognathic surgery due to mono- or bimaxillary dysgnathia. The standardized measurements, based on optical 3D face scans, took place one day before orthognathic surgery (T1) and one day before removal of osteosynthesis material (T2).ResultsSoft tissue changes after procedures involving the mandible showed significant positive correlations and strong soft tissue response (p < 0.05). The midfacial soft tissue response after maxillary advancement was only of minor extent (p > 0.05). The facial surfaces became more symmetric and harmonic with the exception of surgical maxillary expansion, but improvement of facial symmetry revealed no statistical significance.ConclusionSoft tissue response after orthognathic surgery and symmetry are only partially predictable, especially in the maxillary and midfacial region. Computer programs predicting soft tissue changes are not currently safely reliable and should not be used or with caution to demonstrate a patient potential outcome of surgery.     

Three-dimensional assessment of facial soft-tissue asymmetry before and after orthognathic surgery

We developed a new three-dimensional (3D) method of analysis of facial asymmetry and applied it to 44 patients: 20 Class III cases treated by bimaxillary osteotomy; 12 Class III cases treated by maxillary advancement alone, and 12 Class II cases treated by bimaxillary operations. 3D images were taken within a week before operation (T1), and one (T2), three (T3), and six (T4) months after operation. Landmarks were digitised on each 3D model and facial asymmetry scores were calculated. In the bimaxillary osteotomy group, facial symmetry improved after operation. In the maxillary advancement group, there was no notable improvement in facial symmetry after operation. In the bimaxillary group, facial symmetry deteriorated after operation, particularly at the tip of the nose and prominence of the chin. At six months follow-up, the changes in facial asymmetry in the three groups were not significant.     

骨性Ⅲ类错正颌手术前、后面部软、硬组织变化比率的三维研究

目的 研究骨性Ⅲ类错畸形患者面部软、硬组织三维方向上变化的相关性,以及手术前、后软、硬组织的变化比率,以期更好地对术后软组织外貌进行预测。方法 对20例骨性Ⅲ类错畸形成人患者分别于术前2周及术后3个月进行颅面CT扫描和三维重建及面部软组织3D摄影成像,将采集的数据导入Dolphin软件,转换为三维面像数字化模型,建立三维测量坐标系(轴面、矢状面及冠状面),筛选19个软、硬组织标记点并进行测量、对比和配对,共12对。读取标记点的三维坐标（X、Y、Z）,进行手术前、后的定点对比测量,采用 SPSS 22.0 软件包对测量数据进行统计学分析。结果 12对软、硬组织标志点在X轴即左右方向仅Pn/A、Gn'/Gn及Me'/Me存在相关性,在Y轴即上下方向仅Gn'/Gn存在相关性,在Z轴上所有软、硬组织配对点均存在相关性。除UL'/UI及UL/SPr外,均为高度相关。手术前、后,下颌的软、硬组织测量标志点的变化比率大于上颌。结论 骨性Ⅲ类错畸形患者双颌手术前、后软、硬组织的变化主要集中于Z轴即前后向的变化,各软、硬组织配对标志点间呈线性相关关系,且下颌软、硬组织位移比率大于上颌。     

Novel methods for quantifying soft tissue changes after orthognathic surgery

Laser scanners are becoming increasingly important as a tool for quantifying the outcome of facial surgery. However, few computer algorithms have been developed for this purpose. Researchers have either measured the differences in the positions of (manually located) landmarks, or have taken radial measurements of the distances between surfaces. Neither of these techniques provides satisfactory information about the shape changes between surfaces. In this paper, alternative methods are proposed and their performance is compared with that of the radial method. Tests on two patients show that the Correspondences by Sensitivity to Movement (CSM) and closest point algorithms provide the most realistic measurements of the differences between two surfaces. The CSM method was found to be useful for pinpointing areas where the shape has changed.     

Evaluation of facial soft tissue asymmetric changes in Class III patients after orthognathic surgery using three-dimensional stereophotogrammetry

The aim of this study was to investigate changes in facial soft tissue asymmetry over time after orthognathic surgery in Class III patients using three-dimensional stereophotogrammetry. The study included 101 patients with a skeletal Class III malocclusion (72 female, 29 male; age range 19–53 years, mean age 28.6 years) who underwent orthognathic surgery. The minimum follow-up was 12 months. Three-dimensional photographs were acquired using the 3dMDtrio stereophotogrammetry system, and 21 anthropometric landmark positions were evaluated at three time points: before surgery (T0), 6 months (T1) and 12 months (T2) after surgery. Facial asymmetry was assessed and classified as follows: 0–2 mm, mild; 2–5 mm, moderate;> 5 mm, severe. The average distance for whole face asymmetry differed between T0 (median 0.76 mm) and T1 (median 0.70 mm); however, there was no statistically significant difference at any time point. The chin volume asymmetry score differed significantly between T0 (median 1.11 mm) and T1 and T2 (median 1.08 mm for both; P < 0.001 and P = 0.001, respectively), but not between T1 and T2 (P = 0.061). The study findings indicate that the asymmetry of the facial soft tissues has the potential to return after 6 months, without reaching the baseline.     

应用有限元法预测正颌术后三维软组织形变的初步探讨

目的:基于锥形束CT(CBCT)资料建立有限元模型,预测正颌术后三维软组织形变,探讨该方法的可行性与准确性。方法:选取下颌前突患者2例,于术前行颅颌面CBCT扫描,导入Mimics10.01软件,进行软、硬组织三维重建。采用Geomagic Studio11软件进行模型处理,并按实际情况进行手术模拟截骨,导入有限元分析软件AnsysWorkbench 11.0,建立线弹性有限元模型,加载位移后,经分析得出术后软组织三维模样,将其与术后6个月及以上的软组织三维重建图像对比,并进行定性及定量评价。结果:2例患者CBCT资料顺利进行有限元建模及预测,临床定性评价显示2例患者预测结果总体观察相似度高,但在口周及颊部相似度欠佳;Geomagic Qualify11定量检测显示,病例1误差小于2mm的区域为94.98%,病例2误差小于2mm的区域为90.71%。结论:采用线弹性有限元模型预测下颌前突正颌术后的软组织形态是可行的,可为临床提供较为可靠的参考。     

Three-dimensional soft tissue prediction in orthognathic surgery: a clinical comparison of Dolphin,ProPlan CMF,and probabilistic finite element modelling

Three-dimensional surgical planning is used widely in orthognathic surgery. Although numerous computer programs exist, the accuracy of soft tissue prediction remains uncertain. The purpose of this study was to compare the prediction accuracy of Dolphin, ProPlan CMF, and a probabilistic finite element method (PFEM). Seven patients (mean age 18 years; five female) who had undergone Le Fort I osteotomy with preoperative and 1-year postoperative cone beam computed tomography (CBCT) were included. The three programs were used for soft tissue prediction using planned and postoperative maxillary position, and these were compared to postoperative CBCT. Accurate predictions were obtained with each program, indicated by root mean square distances: RMS_Dolphin = 1.8 ± 0.8 mm, RMS_ProPlan = 1.2 ± 0.4 mm, and RMS_PFEM = 1.3 ± 0.4 mm. Dolphin utilizes a landmark-based algorithm allowing for patient-specific bone-to-soft tissue ratios, which works well for cephalometric radiographs but has limited three-dimensional accuracy, whilst ProPlan and PFEM provide better three-dimensional predictions with continuous displacements. Patient or population-specific material properties can be defined in PFEM, while no soft tissue parameters are adjustable in ProPlan. Important clinical considerations are the topological differences between predictions due to the three algorithms, the non-negligible influence of the mismatch between planned and postoperative maxillary position, and the learning curve associated with sophisticated programs like PFEM.