放射定位标记模板技术在牙种植外科前三维影像分析中的应用

目的探讨放射定位标记模板技术在种植手术前三维影像分析中的作用和意义。方法应用空气压模技术制作标记有放射线阻射剂拟种植位点的放射模板,通过牙种植外科石膏模型,受试注塑模型、颅骨颌骨标本及临床种植病人颌骨的螺旋CT扫描,获取颌骨受植区域拟种植部位骨三维结构CT数据。结果确立的扫描平面即调整牙合平面与地面垂直（与X轴坐标线一致）能获得最佳侧断层图像;所有标记的CT模板均可在CT扫描后的轴位图像及颌重建侧断层和全景图像中清晰显现,且能达到准确的标定预种植位点。结论基于放射标记定位模板的评估方法可为种植外科前三维影像分析提供更为精确的手段,更有助于CAD／CAM种植外科定位导向模板的合理设计。     

三维重建技术在口腔虚拟种植导航定位中应用的方法学研究

目的：旨在建立基于CT图像三维重建系统进行颌骨的三维形态、骨量、密度分析和手术设计,最大限度利用牙槽骨骨量且考虑生物力学原理,指导种植手术,提高种植成功率.方法：通过CT采集原始图像数据进行图像二维成像生成全景片、三维数据采样、图像预处理、边缘提取和轮廓跟踪、三维建模及平面拟合、造型显示和交互设计形成三维立体颌骨图像,进行种植动态模拟设计,建立牙种植导航系统.结果：该定位系统对种植的颌骨牙槽骨高度、宽度、形状、骨缺损的准确位置、骨质的密度、骨皮质和骨松质的比例、下颌管的走行、切牙管的位置和大小、颏孔的位置、鼻腔底和上颌窦底的位置和形态等重要结构均能得到良好显示.为人工牙种植术前的手术方案设计提供放射学的颌骨评估基础,建立基于计算机辅助设计、CT图像三维重建口腔虚拟种植导航系统,指导了临床口腔种植体定位设计,大大提高了种植牙手术成功率.结论：基于CT技术三维重建的导航牙种植快速定位系统,极大地提高手术的准确性,种植手术的风险大大减少,达到了牙种植体的智能设计与智能种植,提高牙种植的安全性与成功率     

牙-骨联合支持式CAD/CAM种植手术模板的临床应用

目的:口腔种植体植入位置的正确性与精确性以及方向与深度问题的把握,一直为临床口腔种植外科领域关注的问题.本研究在基于CT影像颌骨三维解剖结构分析的基础上,研究适合国人的计算机辅助设计与制作(CAD/CAM)的口腔种植外科手术模板系统,旨在探讨个体化设计的牙-骨联合支持式CAD/CAM种植手术模板的临床应用效果.材料与方法:应用Philips Brilliance 64层螺旋CT机、CHEU-DENTAL Biostar?空气压模机、SPS600B激光快速原型机并借助Advantage-Dentascan AW4.0软件、ez-DICOM程序、PRO/E及在Visual C++6.0程序设计语言编程下的CISPlan牙种植软件,先后完成研究包括:①基于螺旋CT受植颌骨三维结构分析;②CAD/CAM牙种植外科手术定位导向模板的设计;③12例末端游离缺失患者种植的,临床应用及评价.结果:该辅助软件系统均能满足涉及三维重建、图像分割、图像显示、图像融合等方面的图像处理功能与医学图像的三维可视化,系统可以直接读取DICOM格式、JPG格式和BMP格式的图像数据,实现颌骨CT数据多平面重建与浏览包括轴位、侧断层、全景及受植颌骨三维结构图像的任意剖面的显示.在仿生下颌骨上应用RP技术制作的3、5、10mm三种不同高度的种植外科导向模板进行13mm长度种植体模拟种植的结果提示,5mm以上厚度模板能将植入位点误差控制在1mm以内,角度误差在3度以内.该研究成果为临床研究提供了可靠的实验依据,并为种植外科医生术中准确与精确植入牙种植体提供了安全保障.12例末端游离缺失患者种植外科临床应用效果显示:牙-骨联合支持式CAD/CAM光敏树脂手术模板能满足手术便利、准确、精确与安全的需要.讨论:经临床种植病人初步应用,牙-骨联合支持式CAD/CAM种植手术模板具有如下优点:①将骨支持与牙支持方式结合起来,研制出以模板的骨支持为基础并辅以激光扫描获得的高?     

螺旋X-CT三维成像技术在口腔种植定位中的应用

目的建立螺旋X-CT图像三维重建系统，进行颌骨的三维形态、骨量、密度分析和手术设计，由此制定种植外科手术计划，实现CT三维成像在口腔种植的手术仿真及导航。方法将螺旋X-CT成像技术与计算机图形、图像学原理和三维可视化原理相结合，利用口腔X线Cr序列切片，重构三维实体并获得多平面重组图像，根据图像信息，计算颌骨的骨密度，进行种植动态模拟设计，建立牙种植导航系统。结果该成像技术对种植的颌骨牙槽骨高度、宽度、形状、骨缺损的准确位置、骨质的密度、骨皮质和骨松质的比例、下颌管的走行、切牙管的位置和大小、颏孔的位置、鼻腔底和上颌窦底的位置和形态等重要结构均能得到良好显示。为人工牙种植术前的手术方案设计提供了放射学的颌骨评估基础，建立基于计算机辅助设计、Cr图像三维重建口腔虚拟种植导航系统，指导了临床口腔种植体定位设计。结论螺旋X-CT三维成像技术在口腔种植定位中的应用，极大地提高手术的准确性，种植手术的风险大大减少，达到了牙种植体的智能设计与智能种植，提高牙种植的安全性。     

基于螺旋CT影像的计算机辅助定位阻生牙的临床应用研究

目的探讨计算机辅助技术定位埋伏阻生牙的临床应用价值。方法利用螺旋CT对35例颌骨埋伏阻生牙患者进行颌骨扫描,将DICOM数据输入Simplant软件,通过对颌骨数据后处理定位埋伏阻生牙。结果通过Simplant软件的处理,埋伏阻生牙的三维形态、生长方向、颊舌向和近远中向的位置以及与邻牙和周围解剖结构的关系均得到了清晰显示。结论计算机辅助技术可以精确定位埋伏阻生牙,为制定临床治疗方案提供依据。     

包括牙根三维牙颌模型重建系统的研究

目的获得带有牙根和颌骨的数字化排牙模型,以期纳入牙根和颌骨进行全面三维诊断和治疗。方法将三维螺旋CT图像和层析图像进行整合得到包括牙根和颌骨的三维模型,并在整合模型上进行计算机模拟排牙。结果获得含有牙根和颌骨的三维牙颌模型,在数字化模型上达到牙冠齐整、牙根平行、无牙根外露的排牙效果。结论本研究成功建立包括牙根和颌骨的三维排牙模型,为将牙根和颌骨纳入诊治提供基础。     

种植外科定位模板的制作及CT影像学分析

目的通过种植外科定位模板的制作及计算机断层(Computed Tomography,CT)影像学的分析,便于牙种植体的精确植入及其美学修复。方法选择20例牙列缺损患者,制取上下颌印模,灌注超硬石膏。在石膏模型上根据邻牙及咬合关系制作种植外科定位模板,患者佩戴模板进行CT扫描,利用自主开发的牙颌种植辅助诊断系统V5.4软件对CT数据进行影像学分析。结果 CT影像可以清晰地获得受植区颌骨的三维解剖结构,并能精确地测量受植区骨组织颊(唇)舌向宽度、牙槽嵴顶到下牙槽神经管上壁或上颌窦底的高度、受植区的软组织厚度;还可以测量前牙区理想的种植方向与牙槽嵴方向的差异。植入的种植体位置和方向佳,无术后并发症,且后期修复效果较好。结论种植外科定位模板的CT影像分析可以准确了解种植区骨质,对选择种植体的长度和直径,及其评估后期的种植修复有很大帮助。     

口腔种植计算机术前规划系统的建立与应用

目的：建立口腔颌面计算机术前规划软件系统并进行初步应用。方法：将患者的三维CT数据输入计算机,经空间几何算法、计算机图形学方法及专用语言处理和分析,建立颅颌面骨三维可视化模型,并以Visual C＋＋ 6.0和Visualization Toolkit（VTK）（Kitware）为平台,开发牙列缺损、缺失以及颌骨缺损后应用计算机进行术前评估和种植体植入模拟的应用软件系统。结果：根据临床各种功能需求,建立了针对口腔种植和颅颌面缺损种植修复的系统规划程序。结论：该系统能够实现口腔种植和颌骨缺损种植的术前评估以及各种类型种植体的植入设计与修复,为临床种植提供指导,并为后续基于CT数据的精确导向奠定了基础。     

数字化整合模型技术在DamonQ自锁托槽间接粘接中的初步应用研究

目的探索应用数字化整合模型进行托槽虚拟定位,利用计算机辅助制造托槽间接粘接转移托盘,并试用于临床。方法应用激光扫描的牙冠与CBCT重建的牙根和颌骨整合,建立包括牙冠、牙根和颌骨在内的三维数字化牙颌模型,在整合模型上利用OrthoRx软件进行托槽虚拟定位,并制作托槽间接粘接转移托盘,在临床上通过转移托盘粘接托槽进行矫治。结果OrthoRx软件的托槽虚拟定位,其排牙效果良好,计算机辅助制造产生的间接粘接转移托盘可将托槽转移至患者口中,且托槽粘接稳固。结论 OrthoRx软件可进行托槽在牙面上的虚拟定位,并可呈现排牙后的效果,通过计算机辅助可设计出用于托槽定位的个体化转移托盘,可应用于临床上。     

三维整合牙颌模型在个性化舌侧托槽计算机辅助设计中的应用

目的 采用软件配准的方法建立三维整合牙颌模型,在此模型上进行虚拟排牙和舌侧矫治器设计,以期实现治疗后良好的牙冠牙根排列,为避免正畸治疗后并发症奠定研究基础.方法 选择10例错(牙合)患者进行头颅锥形束CT扫描、牙列石膏模型激光扫描,分别获取三维模型,采用软件配准的方法将两种数字化模型重叠,切除锥形束CT模型牙冠部分,获得三维整合牙颌模型.运用软件自动测量配准误差,采用随机区组设计的方差分析评价3名操作者间差异.对三维整合牙颌模型进行包括牙根的数字化排牙,在排牙模型上进行个性化舌侧托槽计算机辅助设计.结果 3名操作者对上颌或下颌模型配准误差的差异均无统计学意义(P＞0.05);上下颌配准误差分别是(0.144±0.020)和(0.141±0.022) mm;完成上下颌个性化舌侧托槽计算机辅助设计.结论 通过软件配准方法可建立高精度三维整合牙颌模型,并可在虚拟矫治中获得良好牙冠牙根排列,以此为基础可完成个性化舌侧托槽的计算机辅助设计.     

一种适用于口腔三维建模的层析测量法的可靠性研究

目的　应用改进的层析测量法进行无牙颌的三维建模,并对其建模精度进行分析研究。方法　采用改进 的层析测量系统对无牙颌模型逐层切削,进行数据运算,重建无牙颌数字模型。用该方法对10个立方体模型分别 重建数字模型,测量建模前后各条边长的数据,对测量结果进行统计分析。结果　对无牙颌模型逐层切削后获得 完整无牙颌数字模型;10个立方体建模前后的总体误差间无显著性差异(P>0·05);在水平方向建模前后的测量数 据间无显著性差异(P>0·05);在高度方向建模前后的测量数据间存在显著性差异(P<0·01),建模后的小于建模 前(0·09±0·08)mm。结论　改进的层析测量法能够适用于口腔高精度的三维建模。     

Single-step fronto-orbital resection and reconstruction with individual resection template and corresponding titanium implant: a new method of computer-aided surgery

In the cranio-maxillofacial field, computer-aided surgery based on computed tomography (CT) data is becoming more and more important. Navigation systems, which allow the precise intraoperative orientation of surgical instruments, can be used for greater accuracy in determining resection margins of tumours. These techniques support ablative procedures very well, but defect reconstruction still remains a problem. In contrast, computer-aided design (CAD) and computer-aided manufacturing (CAM) systems allow the construction and fabrication of individual templates for bone resection based on coherent numerical 3-D models. The template determines the exact pathway of an oscillating saw so that the planned extent of the resection and, if necessary, also the orientation of the cutting plane are verified. An individual titanium implant is prefabricated with a geometry fitting to that of the template. This implant closes the bone defect so that the contour is reconstructed precisely and individually. This new method was used for the first time for a single-step resection of a meningioma and defect-reconstruction. The tumour which had infiltrated the frontal bone resulting in a protrusion. Fronto-orbital resection and insertion of the titanium implant worked precisely as planned, so that this method offers promising new applications in the field of computer-aided surgery.     

Towards building a photo-realistic virtual human face for craniomaxillofacial diagnosis and treatment planning

The aim of this investigation was to assess the feasibility of building a virtual human face digitally by superimposing a photo-realistic three-dimensional (3D) soft-tissue surface on bone in the correct relationship and evaluating the registration errors associated with this method. The 3D soft-tissue surface of the face was captured using a fast stereophotogrammetry method and the underlying bone was recorded using a 3D computed tomography (CT) scanner. Using the Procrustes registration method, the outer surface of the 3D CT scan and the photo-realistic soft-tissue surfaces were merged into a single Virtual Reality Modelling Language (VRML) file and displayed using a standard VRML viewer. Quantitative measurements of registration errors were calculated in the reconstructed human head models using the signed closest point distance from the photo-realistic skin surface to the transformed CT skin surface. The registration errors between most parts of the aligned surfaces were within +/-1.5mm. The errors were relatively large around the eyebrows, eyelids and cheeks. Simultaneous recording of the face and skull may reduce this error.     

牙颌CT对上颌磨牙近中颊侧第二根管的影像学研究

目的：利用牙颌CT（PROMAX3D）研究活体上颌磨牙近中颊侧第二根管（MB2）口、髓腔形态及其解剖位置关系影像,为临床根管治疗提供可靠的影像学依据。方法：对上颌磨牙根管治疗的患者,使用牙颌CT进行扫描,感兴趣区重建完成之后在颊舌向、水平位以及3D影像上针对上颌磨牙根管数目、牙髓形态影像分析研究。结果：牙颌CT能够在水平位和3D影像上清晰地显示上颌磨牙近中颊侧第二根管的数目、根管口的形态,在颊舌向影像上清楚地显示MB2髓腔的形态及走向。结论：牙颌CT利用不同方向的影像,真实地显示了上颌磨牙近中颊侧第二根管口的形态和髓腔的走向,为临床根管治疗提供可靠的影像学依据,有效地指导了临床医师的治疗工作。     

Three-dimensional fetal cephalometry: an evaluation of the reliability of cephalometric measurements based on three-dimensional CT reconstructions and on dry skulls of sheep fetuses.

AIM: To develop a 3D CT cephalometric analysis for maxillary growth evaluation of sheep fetuses operated in utero, and to evaluate the reliability of this analysis by comparing it with a direct cephalometric analysis on dry skulls. MATERIAL AND METHODS: Five skulls of operated sheep fetuses were used, which after preparation were CT scanned and a 3D reconstruction was performed. A cephalometric analysis was performed directly on the dry skulls as well as on the reconstructed 3D CT images. In total, 56 linear distances were measured. In order to access the error of the method, the procedure was repeated after a 2 week interval. RESULTS: The comparison between the direct cephalometric and the 3D CT analysis revealed that only 5 variables were significantly different. The evaluation of the error of method revealed that 7 variables of the direct cephalometric analysis and none of the 3D CT analysis differed significantly. CONCLUSIONS: According to the results of this study, it can be concluded that a cephalometric analysis on 3D CT reconstructed images of the skulls includes fewer identification errors and seems to be an accurate and reliable method that could be regarded at least as equivalent to conventional cephalometry.     

Assessment of three-dimensional X-ray images: reconstruction from conventional tomograms, compact computerized tomography images, and multislice helical computerized tomography images

Three-dimensional X-ray images (3D images) were used for imaging diagnosis in the oral and maxillofacial region. These images could be fundamentally reconstructed from various tomograms, though clinical 3D images were mainly reconstructed from computerized tomography (CT) images. In this investigation, 3D images were reconstructed from conventional tomograms with a panoramic unit, compact CT images, and multislice helical CT images, and the usefulness of each system was subjectively assessed for dental implant treatment. Three hemilateral dried human mandibles were used and were examined by linear tomography with a panoramic unit, compact CT, and multislice helical CT, and 3D images were reconstructed by using the rendering software for each system. The 3D images were visually evaluated on a 5-point scale covering the alveolar ridge, buccal and lingual bone surface, mental foramen, and tooth sockets. As a result, 3D images reconstructed from conventional tomograms with the panoramic unit were assessed as fair to unsure, compact CT 3D images were assessed as unsure to good, and multislice helical CT 3D images were assessed as good to excellent. It was concluded that compact CT 3D images and multislice helical CT 3D images were useful in dental implant treatment.     

Automatic extraction of the mid-facial plane for cranio-maxillofacial surgery planning

Recently developed computer applications provide tools for planning cranio-maxillofacial interventions based on 3-dimensional (3D) virtual models of the patient's skull obtained from computed-tomography (CT) scans. Precise knowledge of the location of the mid-facial plane is important for the assessment of deformities and for planning reconstructive procedures. In this work, a new method is presented to automatically compute the mid-facial plane on the basis of a surface model of the facial skeleton obtained from CT. The method matches homologous surface areas selected by the user on the left and right facial side using an iterative closest point optimization. The symmetry plane which best approximates this matching transformation is then computed. This new automatic method was evaluated in an experimental study. The study included experienced and inexperienced clinicians defining the symmetry plane by a selection of landmarks. This manual definition was systematically compared with the definition resulting from the new automatic method: Quality of the symmetry planes was evaluated by their ability to match homologous areas of the face. Results show that the new automatic method is reliable and leads to significantly higher accuracy than the manual method when performed by inexperienced clinicians. In addition, the method performs equally well in difficult trauma situations, where key landmarks are unreliable or absent.     

上颌埋伏尖牙CT影像分型系统的建立和分析

目的 利用螺旋CT三维重建技术建立适合上颌埋伏尖牙的影像学分型系统。方法 选择102例上颌埋伏尖牙患者为研究对象,共121颗上颌埋伏尖牙。所有患者均接受标准的螺旋CT扫描,数据均导入MIMICS 10.01软件采用表面遮盖成像法进行三维重建。通过对121颗上颌埋伏尖牙的三维空间位置进行分析建立上颌埋伏尖牙的影像学分型系统。结果 本研究建立了一个上颌埋伏尖牙的三维CT影像学数据库。研究结果显示在X轴方向上,最常见的分型是牙尖近中伴根尖正常。在Y轴方向上,样本中所有埋伏尖牙只存在3种分型即根尖均处于高位,牙尖分别处于高、中、低位。在Z轴方向上,最常见的分型是牙尖和根尖均处于唇侧,约占总数的三分之一。结论 本研究利用螺旋CT建立了一个适合上颌埋伏尖牙的三维影像学分型系统,具有一定的临床诊断价值。     

The use of a new 3D splint and double CT scan procedure to obtain an accurate anatomic virtual augmented model of the skull

Three-dimensional (3D) virtual planning of orthognathic surgery requires detailed visualization of the interocclusal relationship. The purpose of this study was to introduce the modification of the double computed tomography (CT) scan procedure using a newly designed 3D splint in order to obtain a detailed anatomic 3D virtual augmented model of the skull. A total of 10 dry adult human cadaver skulls were used to evaluate the accuracy of the automatic rigid registration method for fusion of both CT datasets (Maxilim, version 1.3.0). The overall mean registration error was 0.1355+/-0.0323 mm (range 0.0760-0.1782 mm). Analysis of variance showed a registration method error of 0.0564 mm (P < 0.001; 95% confidence interval = 0.0491-0.0622). The combination of the newly designed 3D splint with the double CT scan procedure allowed accurate registration and the set-up of an accurate anatomic 3D virtual augmented model of the skull with detailed dental surface.