【作者】 程筱胜；

【导师】 廖文和；

【作者基本信息】 南京航空航天大学 ， 航空宇航制造工程， 2007， 博士

【摘要】 随着三维测量、离散曲面造型、高硬度材料快速加工等方面技术的进步,口腔修复体CAD/CAM医疗装备在近十多年里得到了飞速的发展,正推动着新时期的“牙科技术革命”。本文结合口腔临床医学应用实际,以口腔修复曲面设计技术为研究对象,系统研究了口腔修复曲面设计系统的相关基础理论、方法及关键技术。本文主要研究内容和创新成果如下:(1)研究了修复体三角网格模型的快速拓扑重建技术,提出了采用顶点一环邻域的拓扑结构对三角网格模型进行快速重建,并对基于Hash和二叉树的冗余点滤除算法进行了分析研究,设计了相关的数据结构,可以快速高效的完成三角网格模型的拓扑重建。(2)提出基于顶点法矢的等距和基于隐式曲面的等距的两种算法。采用了八叉树空间分块进行数据点采样,以及顶点映射结合原始模型拓扑关系来生成网格化隐式等距曲面,并通过实例分析了两种等距算法的优缺点以及适用范围。(3)提出了口腔牙齿预备体颈缘线半自动自适应提取算法,口腔医生仅需要利用自己的医学经验在颈缘附近顺序交互拾取有限关键特征点,就可以半自动、可靠地完成颈缘线的准确提取。(4)研究了修复体三角网格裁剪技术,提出一种新的面向口腔修复设计的颈缘线裁减算法,通过粗裁减-精裁减-边界优化三个步骤,可靠、高效地完成了三角网格曲面裁减过程,并已经在临床开展应用试验,取得了满意的效果。(5)研究了修复体三角网格孔洞修补和缝合技术,提出了网格孔洞修补与缝合按统一思想处理的算法。该算法对网格模型进行孔洞修补、缝合可以得到与原始网格模型密度相近,且边界光滑连续的投影网格。(6)针对口腔修复临床工作的实际需要,采用UML技术对口腔修复曲面设计系统进行建模,在此基础上,开发了面向口腔修复曲面设计系统软件原型系统--DentalCAD,并将其应用到临床口腔修复体设计中,验证了系统的实用性和有效性。更多还原

【Abstract】 With advances in measurement technology, discrete surface modeling and efficient processing technology of high hardness materials, both the software and hardware of the dental CAD/CAM system and equipment have achieved rapid development in the past 20-odd years. The dental CAD/CAM system and equipment are pushing forward a new era of dental restoration. Based on clinical science of stomatology, the research of this dissertation mainly focus on areas of the relevant basic theories, methodologies and key technologies of dental surface design and its extended applications in the dental CAD/CAM.The main innovative contributions of this dissertation are as follows:Firstly, to reconstruct the topology relation of the discrete surface model efficiently and completely, this dissertation has designed a new type of data structure used for the discrete surface model based on vertex’one ring neighborhoods. This dissertation has analyzed the performance and efficiency of the redundant points filtering algorithms used in the process of the topology reconstruction based on hash table and RB binary tree data structure comparatively, and has also designed the node structs stored in hash table and RB binary tree respectively. The experimental results show whichever filtering algorithm chosen: the time complexity of the surface reconstruction is less than O(NlogN), where N is the vertices total number of the discrete surface model.Secondly, this dissertation presents two kinds of surface offsetting method for the discrete surface model based on vertex normal vector and implicit surface respectively. In the process of surface offsetting based implicit surface method, the spatial data block sampling technique using octree data structure, vertices mapping technique based on Newton’iteration method and the original topology relation of the discrete model are used. Which offsetting method is more suitable when offsetting different discrete models is analyzed through lots of experiments.Thirdly, this dissertation presents a semiautomatic & Adaptive Algorithm for the preparation line extraction. The dentists only need to pick up some limited points in order near the real preparation line of the discrete model interactively, according to their clinical experiences. After that, the system can complete the preparation line extraction automatically.Fourthly, the trimming technique for discrete models is researched, and presents a newly trimming algorithm specifically for dental restorations. The presented trimming algorithm is composed of three steps including coarse trimming, fair trimming and boundary optimization, and has been applied in clinical trials proved efficiently and achieving satisfactory results.Fifthly, this paper presents a uniform processing method for triangular mesh’s hole filling and stitching. The mesh patch obtained after hole filling or stitching using the presented method can fit across the boundary (boundaries) smoothly and continuously. the uniform processing method is proved efficiently and robust in many experiments of different kinds of boundary conditions including filling and stitching.Sixthly, the general model for dental restorations is given using UML according to the practical demands in clinical prosthodontics. Based on that, the dental restoration-oriented modeling software prototype system (DentalCAD system) is developed. Practicability and validity of the system are proved in clinical applications更多还原