【作者】 张春光；

【导师】 顾晓明； 张琪；

【作者基本信息】 河北医科大学 ， 口腔临床医学， 2009， 硕士

【摘要】 目的对称,是正常人体和人体美学的基本要素之一。不对称性畸形是先天性和后天性颅颌面畸形中最常见的形式,严重影响患者容貌和心理。对严重的不对称性颅颌面畸形,以往单纯的手术方法很难达到对称性修复重建的目的。本研究基于反求工程(reversed engineering)原理,利用数字化工程技术试图解决严重颅颌面畸形修复重建中的精确化问题。实验通过采集CT数据、CAD/CAM、快速成型(rapid prototyping, RP)技术、数控铣削技术,利用新鲜猪头进行头骨的头模及个体化补件的制作,通过对实体、CT、三维重建及头模标志点间距离的测量,比较基于RP技术的头颅模型制作过程中各环节所产生的误差;通过对实体、补件树脂模型及纯钛补件各项数据的测量,比较钛补件、补件树脂模型与实体间是否存在误差,并将此修复方法用于临床修复颅颌面缺损,观察临床效果。方法动物实验部分以市售新鲜检疫后的4个猪头为实验对象,通过对称选取3组标志点,用钛钉(中邦公司长12mm、直径2mm)垂直于骨面钉入标志点作为标志。这3组标志点分别是额骨与上颌骨相交骨缝的眶缘点,颞骨颧突与颧骨颞突相交“>”型骨缝的尖端,下颌角点。然后进行CT扫描,得到整个猪头的CT断层数据,以医学数字图像通讯格式(digital imaging and communications in medicine, DICOM)刻成光盘。最后将新鲜猪头的软组织去除,制成猪头头骨标本。实验一利用猪头的CT断层数据进行猪头头模的制作,首先将CT数据导入3DMSR(3-dimension medicine surface renderin)软件中进行猪头头骨三维曲面重建,得到三维图像,再将三维图像数据以.stl文件格式传输至快速成型机制作猪头RP树脂头模。分别测量头骨实体、CT断层图像、3D MSR软件中三维曲面重建图像及头骨RP树脂头模上对称标志点间的距离,比较四组数据是否存在差异,并得到各加工环节产品与实体间的具体误差。实验二在猪头头骨标本上设计一侧颧弓部的截骨范围,并按设计截取这段颧弓待测。然后利用CT扫描断层数据输入3D MSR软件中进行猪头头骨骨面三维曲面重建,将三维曲面重建图像传至Surfacer9.0软件中进行模拟截骨,根据在实体标本的设计,虚拟截取相同的一段颧弓,将截取的颧弓的截面进行修整,得到截取颧弓的三维模型,再将三维模型数据分别传至快速成型机及数控机床制作该段颧弓的补件树脂模型及钛补件。最后测量截取的颧弓的实体、补件树脂模型及钛补件的各向数据,统计学比较三组间是否存在差异,统计处理两种制作方法与实体间的误差及两种制作方法间的误差。临床部分,利用动物实验制作补件树脂模型及钛补件的方法,应用镜像技术(mirror technique)设计补件模型,在树脂头模上试装并修改后,用数控铣削法制作纯钛补件,通过适当的手术入路完成颅颌面缺损或发育畸形的修复重建7例,取得满意的临床效果。结果动物实验及临床应用结果显示:利用CT数据、CAD/CAM、快速成型技术制作的三维头颅模型能详尽、直观、立体的再现机体的三维解剖结构,利用镜像技术个体化制作的修复体补件与缺损具有极强的适配性,能达到对称修复的目的。1通过对实体、CT断层图像、三维重建图像及RP树脂头颅模型的对称标志点间距离的测量,用方差分析得到四组数据间无显著性差异(F=0.021,P=0.996>0.05)。2对称性标志点间的误差: CT与实体间误差为1.54±1.31mm,三维重建与实体间的误差为2.62±1.64mm,RP树脂头模与实体间的误差为1.89±0.79mm。CT、三维重建及RP树脂头模的测量结果均较实体测量结果放大,其中放大程度最大为三维重建,最小为CT扫描。3猪头头骨经过双侧组织的边缘提取后,两侧标志点间距离所产生的误差为0.09~3.03mm ,平均值为1.89±0.79mm,单侧组织边缘提取后,一侧骨面至中线所产生的误差为0.05~1.52mm,平均值为0.94±0.40mm。4根据实体和截取部分颧弓制作的补件树脂模型及纯钛补件进行各向数据测量得到三组数据,采用方差分析得到三组间无明显差异(F=0.497,P=0.615>0.05)。5纯钛补件与实体间误差为1.16±0.39mm,补件树脂模型与实体间误差为1.17±0.47mm,纯钛补件与补件树脂模型间误差为0.00±0.26mm。补件树脂模型、纯钛补件较实体均有放大,补件树脂模型与纯钛补件间误差可以忽略。6临床应用中通过制作补件前设计的手术入路,很容易将补件置入需要重建的部位,补件的骨面部分与受床适配性很好,大大缩短了手术时间,简化了手术操作,减少了手术创伤,术后外形的对称性恢复满意,在2年多随访期间未发现不良反应和功能障碍。结论1三维头颅模型能直观、详尽的反映机体的三维解剖结构及病变缺损的形状、大小,个体化修复体与缺损具有极强的适配性,能达到对称修复的目的。2三维头颅模型及纯钛补件所产生的误差主要来自于图像的处理过程,此过程中CT数据的提取及三维重建后表面光滑处理,为产生误差的主要原因。3数字化颅颌面修复重建技术在临床应用中使修复的效果更加真实、满意,并且简化了术中操作,缩短了手术时间,减少了手术创伤,近期整复效果满意。4虽然本研究发现的实体与用RE技术制作的修复体补件间的误差在实际修复重建手术中可以被视觉忽略,但考虑到硬组织的增容与软组织的扩张之间存在的不一致性,在实际应用中是否需要对修复体补件进行适当的修改或补偿,尚有待进一步研究。更多还原

【Abstract】 Objective: Symmetry is essential for a normal, healthy person. Asymmetry anisotropy is typical in craniomaxillofacial deformities, which seriously distorts patients’ figure and psychology. Classical plastic and reconstructive surgery has not been very effective in correcting serious asymmetrical deformity in the past due to lack of precision. This study aims to improve this precision by using digital craniomaxillofacial plastic and reconstructive surgery based on principals of reversed engineering. The study used fresh pigs’ heads as samples. Experimental processes included collecting CT data, CAD/CAM, rapid prototyping (RP), and computer-aided milling. This produced skull molds of the pigs’ heads and individual implant pieces. Then, measurements were taken from the skull entities, CT images, 3-D reconstruction images and the RP resin model, and the measurements were compared to find the error generated within each stage, as well as the overall difference between the final skull molds and the skull entities. Finally the technique was applied in clinic to repair craniofacial defects and clinical effects were observed.Methods: Part 1 was animal experiments. Experimental objects were 4 fresh pigs’ heads. Three groups of symmetry markers were chosen for measurements on the pigs’ heads, and were identified by inserting titanium screws into the marking points. Then, the pigs’ heads were scanned with CT. The CT data were written on a disc in DICOM format. After this step, skull specimen of the pigs’ heads were made. Experiment 1: CT data were imported into 3-D MSR software to perform a visible 3-D surface reconstruction. The 3-D reconstruction images were exported to rapidform in .stl format for RP resin model manufacture. The distance between the symmetry markers were measured and results were compared among the skull entities, CT data, 3-D reconstruction images and the resin model. Experiment 2: A designed region from one side of zygomatic arch was cutoff from the pig’s skull specimen. A CT scan was made to the remaining part of the skull specimen, and CT data were imported into 3-D MSR for a 3-D surface reconstruction. Export the reconstruction image into Surfacer9.0 software to perform a virtual osteotomy of the same region. The digital piece was then sent for rapid prototyping and computer-aided milling respectively for manufacture of resin model and titanium implant. At last, the piece of zygomatic arch and both resin model and titanium implant were measured and compared statistically to find the differences between manufacture methods and entity.Part 2 was clinical practice. Seven patients suffered craniomaxillofacial defects were successfully repaired with customized digital implants using above mentioned techniques through proper surgical approach.Results: The results of animal experiments and clinical application showed that the resin model of skull made by digital engineering technique duplicated its entity very well in structure. The customized digital implants made with mirror technique adapted to the surface of the defect very well. The results of symmetrical repair and reconstruction for asymmetrical deformity of craniomaxillofacial region were satisfactory.1 Through measuring the distances between the symmetry markers on skull entities, CT images, 3-D reconstruction images and the RP resin model, the result of analysis of variance did not show significant differences among four groups (F=0.021, P=0.996>0.05).2 Compared to the skull entity, the errors in distance between symmetrical markers were as follows: 1.54±1.31mm for CT images, 2.62±1.64mm for 3-D reconstruction images, 1.89±0.79mm for RP resin models.3 For RP resin models compared to the entity, average error in distance between symmetrical markers was 1.89±0.79mm (0.09~3.03mm), and average error in distance between symmetrical marker and the middle line was 0.94±0.40mm (0.05~1.52mm).4 In comparison of the measurements among the zygomatic arch, the RP resin model and the titanium implant, analysis of variance among the three groups did not show significant differences (F=0.497,P=0.615>0.05). 5 The error between titanium implant and skull entity was 1.16±0.39mm, the error between RP model and skull entity was 1.17±0.47mm, the error between titanium implant and the RP resin model was 0.00±0.26mm.6 In clinical application, the surgical approach must be firstly taken into account because of irregular shape of customized implant. Then the digital implant will be fixed to the defect very easily. The implant adapts the surface of the defect very well. The operative time is significantly shortened, the surgical procedure simplified, the trauma of operation decreased, the symmetry of patient’s appearance satisfied. During 2 years follow-up, no obvious side effects and dysfunctions were found.Conclusion1 The RP skull model can reflect three-dimensional anatomy of the skeleton intuitively and in detail. Customized implant made by digital engineering adapts the surface of defect and the result of surgery was satisfied.2 The errors between RP skull model and titanium implant to the skull entity arise mainly from treatment process of the image. In these processes, CT data extraction and the surface treatment after visible three-dimensional reconstruction are the main reason for the errors.3 During 2 years follow-up, the results of digital craniomaxillofacial plastic and reconstructive surgery were satisfactory, which has simplified the operation, shortened the operative time, and decreased the operative trauma.4 Although the error between digital titanium implant and skull entity can be visibly neglected in clinic, there is discordance of augmentative quantity between hard and soft tissues. It needs further investigation whether or not to compensate the customized implant in the process of design and manufacture.更多还原