基于二维DR的颅面硬组织与软组织拟合的研究

目的:以数字化X线摄影片(digital radiograph,DR)图像和激光扫描为数据源,三维重建颅面硬组织和软组织,并进行硬软组织的有效拟合,以期为治疗方案确定、手术方法选择和提高医患交流的水平提供平台.方法:在志愿者面部贴定铅点,拍摄头颅正侧位DR片.利用基于二维DR数据的颅面硬组织三维重建系统进行硬组织形变建模.获得颅面部硬组织模型.利用激光扫描数据进行面部软组织三维重建,获得面部软组织三维模型.然后通过铅点坐标的匹配,将颅面硬组织与面部软组织进行拟合.结果:分别重建了能反映真实颅面部组织结构的硬组织三维模型和面部软组织三维模型,并实现了颅面部硬组织与软组织的有效拟合.结论:本研究实现了颅颌面三维结构的有效重建和拟合,为进一步进行正颌手术模拟和容貌预测奠定了基础.拟合结果真实可靠,能够用于临床.     

基于二维DR数据的颅面硬组织三维重建精度分析

目的:验证二维DR数据形变重建的颅面硬组织模型的准确性,以期为治疗方案确定、手术方法选择和提高医患交流水平提供平台.方法:对7名志愿者分别进行基于二维DR数据的形变建模和CT建模,通过测量64项描述颅面硬组织特征的项目,进行直观重叠比较和客观分析.采用SPSS 17.0软件包对数据进行配对t检验.结果:58项测量项目无显著差异,形变建模和CT建模的一致性很高.结论:基于二维DR数据形变建模的颅面硬组织精确性高,偏差基本在允许的范围内,完全可以满足临床诊断和治疗的需要.该三维重建系统能够在临床上应用.     

颅颌面三维可视化模型的构建及应用

目的:构建基于CT影像数据的颅颌面硬软组织三维可视化模型,为进一步的三维分析诊断、手术模拟和预测构建基础平台.方法:系统获取患者CT颅颌面扫描的原始数据,经过二维预处理,三维预处理,运用改进的移动立方体算法,即移动四面体法完成基于断层图像的三维表面重建;运用基于小波的脚印法实现体重建,最终获得颅颌面三维可视化模型.结果:颅颌面三维可视化模型能够清晰地显示颅颌面复杂结构完整的形态,清楚的表面.临床医生能够对重建的三维模型动态旋转,从任意视角观察颅颌面软硬组织的畸形特征,也能通过任意切割显示颅颌面内部解剖结构.同时它具备良好的用户界面,临床医生使用方便.结论:解决了金属托槽X线反射、患者X线照射剂量及重建时间效率等问题,达到了预先设计目标,能够在临床得以实际应用.     

标准牙冠三维模型的建立及其可操作平台的研究

目的 建立标准牙冠的计算机三维模型以及开发其可操作的软件平台。方法 利用三维激光扫描仪扫描全牙列28颗标准牙冠的石膏模型，编写程序对获得的数据进行处理，重建各牙冠的三维图形，并结合国人牙冠的平均测量数据对其进行调整，同时在牙冠表面定义特征区和特征点，利用程序对牙冠进行各种变换和调整。结果 扫描仪获取了牙冠数据，系统重建了各牙冠的标准三维图形，可对牙冠进行各种变换使其产生位移、旋转和整体形变，按照各牙冠的解剖特点及正中He时的咬合接触定义了特征区，特征区可以在空间三个方面上产生指定形变。结论 标准牙冠的三维计算机模型精确可靠，其操作平台实现了多种功能，为进一步开发打下了基础。     

颅面部三维图像融合技术的研究进展

颅面部三维图像融合技术在现代正颌外科、颅颌面整形重建外科及口腔正畸等学科的颅面人体测量、颜面结构评价、颅面畸形临床诊断、治疗计划制订、手术模拟和术后效果预测等方面,具有其他影像技术无法比拟的独特优势,具有良好的应用价值和前景.本文就颅面部三维图像融合技术的模式选择、基本原理、特点及其应用的研究进展作一综述.     

标准牙冠计算机三维图形的重建及其空间几何变换的研究

目的：实现标准牙冠的整体几何变换以及咬合面局部的微小形变，模拟修复体的咬合调整。方法：利用Natlab软件平台编写程序，在标准牙冠的表面定义特征点和特征区，利用矩阵运算的方法对标准牙冠的三维数据进行各种数学变换。结果：重建了标准牙冠的三维图形，实现了牙冠的空间整体几何变换和局部形变。结论：模拟了修复体咬合调整的过程，为以后CAD软件的设计提供了有益的思路。     

头影测量标志点计算机自动识别的初步研究

目的初步探讨计算机头影测量自动定点技术。方法随机选择20张头颅侧位片作为待测图像,另选1张高质量的X线片为标准图像。使用仿射变换结合模板匹配的方法来识别标志点。首先在标准图像上手工确定各标志点的位置并建立标志点的标准模板;然后用仿射变换的方法把标志点从标准图像变换到待测图像上,获得标志点的初始位置;最后经模板匹配确定标志点的准确位置。结果共识别出11个硬组织点和10个软组织点。硬组织点平均误差2.28 mm,软组织点平均误差0.77 mm。有4个硬组织标志点的定点误差<2 mm。结论初步建立了头影测量标志点自动识别系统,但整体上标志点识别的准确性尚不能满足临床应用要求。     

蒙古族正常成年人颅颌面硬组织的三维CT测量研究

目的研究蒙古族正常成年人颅颌面硬组织的三维头影测量正常值,为正颌外科提供临床诊断、治疗计划及手术方案制定的数字依据。方法对48名符合正常标准的三代蒙古族后裔成年人进行颅颌面螺旋CT薄层扫描,用三维软件重建颅颌面硬组织三维图像,在屏幕上定点测量37项线距和19项角度。结果获得了蒙古族正常成年人颅颌面硬组织双螺旋CT三维头影测量正常值。结论①蒙古族正常成年人颅颌面硬组织的差异主要体现在骨骼大小上,而在骨骼轮廓和比例关系上差异较小,蒙古族女性的下颌开张度大于男性,而男性较女性面部前凸。②蒙古族正常成年人颅颌面硬组织结构左右也存在着一定程度的属于正常形态变异的不对称现象。③蒙古族正常成年人颅颌面硬组织形态具有明显的性别差异及种族特点,在正颌外科的临床诊断、治疗计划、手术方案的制定及术后面形预测应参考蒙古族自身的正常值。     

蒙古族正常(牙合)成年人颅颌面硬组织的三维CT测量研究

目的研究蒙古族正常耠成年人颅颌面硬组织的三维头影测量正常值，为正颌外科提供临床诊断、治疗计划及手术方案制定的数字依据。方法对48名符合正常铪标准的三代蒙古族后裔成年人进行颅颌面螺旋CT薄层扫描，用三维软件重建颅颌面硬组织三维图像，在屏幕上定点测量37项线距和19项角度。结果获得了蒙古族正常耠成年人颅颌面硬组织双螺旋CT三维头影测量正常值。结论①蒙古族正常耠成年人颅颌面硬组织的差异主要体现在骨骼大小上，而在骨骼轮廓和比例关系上差异较小，蒙古族女性的下颌开张度大于男性，而男性较女性面部前凸。②蒙古族正常耠成年人颅颌面硬组织结构左右也存在着一定程度的属于正常形态变异的不对称现象。③蒙古族正常耠成年人颅颌面硬组织形态具有明显的性别差异及种族特点，在正颌外科的临床诊断、治疗计划、手术方案的制定及术后面形预测应参考蒙古族自身的正常值。     

应用B-样条技术重建颅颌骨的三维形态

目的:本研究试图找到最能表达颅颌骨特征的特征点,并尝试运用计算机图形学的技术拟合生成颅颌骨的 曲线和曲面图。方法:头颅骨标本经CT断层扫描后获得三维数据,经过筛选提取出76个特征点,应用B-样条技 术拟合生成颅颌骨的曲线和曲面图。结果:生成的图像可视性强,定性地描述了颅颌骨三维形态。结论:根据特 征点重构颅颌骨的三维可视图是可行的,为下一步直接从X线定位片获得颅颌骨的特征点并重建颅颌骨的三维形 态提供了依据。     

Clinical applications of 3-D CT and 3-D plastic model in the maxillo-facial region

We compared the usefulness of 3-D plastic models with that of 3-D CT images with regard to their applications in the field of maxillo-facial medicine. We also considered possibilities for wider clinical applications for both these methods. Five patients with the following conditions were involved in this study: hyperplasia of the mandibular condyle, 1; fracture of the maxilla and mandible, 1; coronoid hyperplasia, 2; and unilateral temporomandibular joint ankylosis with microgenia, 1. Stereolithographic models and 3-D CT images were made for each patient. CT and 3-D CT images were superior to plastic models with respect to their clinical diagnostic value. Furthermore they provided more precise information about the surface and inner structures of the jaws. 3-D plastic models made it possible to do close observation of the complex anatomical relationship of the region which were easily overlooked on axial CT images and even on 3-D CT images. The 3-D plastic models were useful for simulated surgery in all these cases. In the cases with bilateral coronold process hyperplasia, the plastic model well clarified the direct functional cause of the patients trismus. The analysis on plastic models suggested that the abnormal contact of the coronold process with the deformed surrounding anatomical structures might cause trismus and elongation of the process. We believe that plastic models can be applied to other dental fields such as dental implantology, prosthodontics and measuring for 3-D cephalometry.     

A new method of 3-D cephalometry Part I: the anatomic Cartesian 3-D reference system

The purpose of this study was to present a new innovative three-dimensional (3-D) cephalometric method. Part I deals with the set-up and validation of a voxel-based semi-automatic 3-D cephalometric reference system. The CT data (DICOM 3.0 files) of 20 control patients with normal skeletal relationships were used for this study. To investigate accuracy and reliability of the 3-D cephalometric reference system (Maxilimtrade mark, version 1.3.0) a total of 42 (14 horizontal, 14 vertical and 14 transversal) orthogonal measurements were performed on each patient twice by each of two investigators. The intra-observer measurement error was less then 0.88 mm, 0.76 mm and 0.84 mm for horizontal, vertical and transversal orthogonal measurements, respectively. The inter-observer measurement error was less as 0.78 mm, 0.86 mm and 1.26 mm for horizontal, vertical and transversal orthogonal measurements, respectively. Squared correlation coefficients showed a high intra-observer and inter-observer reliability. The presented 3-D cephalometric reference system proved to be accurate and reliable and can therefore be used for 3-D cephalometric hard and soft tissue analysis.     

2-D and 3-D reconstructions of spiral computed tomography in localization of the inferior alveolar canal for dental implants

OBJECTIVE: The purpose of this study was to compare and validate the accuracy of measurements on 2-dimensional and 3-dimensional reconstructions from spiral computed tomography in localization of the inferior alveolar canal. STUDY DESIGN: Four edentulous human cadaver heads with intact mandibles were imaged in a spiral computed tomography scanner. The data were transferred to a networked computer workstation to generate 2-dimensional orthoradially reformatted and 3-dimensional volumetric images. Linear measurements of the images were made from the superior border of the inferior alveolar canal to the alveolar crest. The specimens were then dissected at corresponding locations, and physical measurements were made. RESULTS: There were no statistically significant differences between the 2-dimensional computed tomography measurements and the physical measurements or between the 3-dimensional computed tomography measurements and the physical measurements. However, we did find a statistically significant difference between the 2-dimensional and 3-dimensional computed tomography measurements. CONCLUSIONS: 2-dimensional and 3-dimensional computed tomography images allow accurate measurements for localization of the inferior alveolar canal.     

3-D COSMOS: a new 3-D model based computerised operation simulation and navigation system.

A new three-dimensional (3-D) model based system for preoperative planning, simulating the operation and transfer of the operation from 3-D model to patient (navigation) is to be introduced. A computer controlled digitizer with specially designed software enables 3-D measurement and symmetry analysis on the 3-D model with a precision better than 0.01 mm (SD: 0.05 mm, range: -0.2 to +0.04 mm). Translocations of the jaws during simulation are electronically registered with 6D-position sensors and displayed graphically and numerically on the PC screen (measurement accuracy 0.01 mm, 0.002 degrees). A precise transfer of positional data from the model to the patient in the operating theater is necessary if 3-D model operations are to be made. The position transfer (navigation) system to be introduced depends on a neurosurgical headframe on the patient, enabling an easy and three-dimensionally precise transfer of the planned jaw position to the patient. The three-dimensional precision of the positional transfer is 0.05 mm (SD: 0.144 mm, range: -0.36 to +0.69 mm). This new method allows for the first time exact three-dimensional simulation of operation and precise transfer to the patient. Especially in the case of asymmetric malformation and complex dysgnathia, the new method facilitates optimal symmetric and aesthetic results.     

3-D analysis of dislocation in zygoma fractures

ObjectiveWhen fractured, zygomas rotate and dislocate. The present study quantitatively elucidates the pattern of the rotation.Methods50 patients with tri-pod-type zygoma fractures were involved in this study. After defining a 3-dimensional coordinate system – consisting of the M–L axis (the axis directed from the medial to lateral side of the skull), I–S axis (directed from the inferior to superior side), and P–A axis (directed from the posterior to anterior side), the degree with which the fractured zygomas rotated around each of these axes was measured using 3-dimensional graphic software. Thereafter, the tendency of the rotation was compared between the three rotational axes.ResultsRotation around the I–S axis was the most frequent with a 96% incidence, followed by a substantial margin by rotation around the M–L axis with a 26% incidence; rotation around the P–A axis was rare, with an incidence of 10%. Furthermore, the degree of P–A axis rotation was minor compared to I–S and M–L axis rotations.ConclusionThe main factor of zygoma dislocation in zygoma fracture is rotation around the I–S axis. This finding is helpful for effective performance to reposition fractured zygomas.     

牙列缺损的计算机三维建模

目的 建立牙列缺损的计算机三维模型。方法 采用表面绘制法,依据CT扫描头颅骨标本获得的二维断层图像数据在3D Studio Max中沿牙体长轴放样、微调并赋以材质,得到牙列缺损的计算机三维模型。结果 能在计算机中方便快速地模拟任意类型的牙列缺损,并可全方位地旋转、放大和缩小。结论 提供了一种牙列缺损三维建模的新方法,有利于三维义齿专家系统的开发和计算机辅助教学。