University of Passo Fundo, Post-graduate Program in Dentistry, Passo Fundo, RS, Brazil.
J Dent. 2013 May;41(5):412-9. doi: 10.1016/j.jdent.2013.02.014. Epub 2013 Mar 6.
To describe and apply a method of modelling dental crowns and three-unit fixed partial dentures (FPD) for finite element analyses (FEA) from 3D images obtained using a micro-CT scanner.
A crown and a three-unit fixed partial denture (FPD) made of a ceramic framework (Y-TZP) and veneered with porcelain (VM9) were scanned using an X-ray micro-CT scanner with a pixel size of 6.97 μm. Slice images from both structures were generated at each 0.034 mm and processed by an interactive image control system (Mimics). Different masks of abutments, framework and veneer were extracted using thresholding and region growing tools based on X-ray image brightness and contrast. 3D objects of each model were incorporated into non-manifold assembly and meshed simultaneously. Volume meshes were exported to the FEA software (ABAQUS), and the load-generated stress distribution was analyzed.
FEA models showed great shape resemblance with the structures. The use of non-manifold assembly ensured matching surfaces and coinciding nodes between different structural parts. For the crown model, tensile stresses were concentrated in the internal surface of the core, near to the applied load. For the FPD model, the highest tensile stresses were located in the framework, on the cervical area of connectors and pontic.
Valid 3D models of dental crown and FPD can be generated by combining micro-CT scanning and Mimics software, emphasizing its importance as design tool in dental research.
The 3D FEA method described in this work is an important tool to predict the stress distribution, assisting on structural design of dental restorations.
描述并应用一种从使用微计算机断层扫描 (micro-CT) 扫描仪获得的 3D 图像中对牙冠和三单位固定局部义齿（FPD）建模的方法，以进行有限元分析（FEA）。
使用具有 6.97μm 像素大小的 X 射线微计算机断层扫描 (micro-CT) 扫描仪对陶瓷基底（Y-TZP）制成的牙冠和三单位固定局部义齿（FPD）进行扫描，并对其进行上瓷（VM9）处理。从这两种结构中以 0.034mm 为间隔生成切片图像，并通过交互式图像控制系统（Mimics）进行处理。使用基于 X 射线图像亮度和对比度的阈值和区域生长工具提取基牙、基底和瓷层的不同蒙版。将每个模型的 3D 对象合并到非流形装配中并同时进行网格划分。将体积网格导出到 FEA 软件（ABAQUS）中，并分析产生的载荷下的应力分布。
FEA 模型与结构具有很大的形状相似性。使用非流形装配确保了不同结构部分之间的匹配表面和重合节点。对于牙冠模型，拉伸应力集中在核心的内表面，靠近施加的载荷。对于 FPD 模型，最高的拉伸应力位于基底的颈部区域和连接体和桥体上。
通过结合微计算机断层扫描和 Mimics 软件，可以生成牙冠和 FPD 的有效 3D 模型，强调了其作为牙科研究设计工具的重要性。
本文描述的 3D FEA 方法是预测应力分布的重要工具，有助于牙科修复体的结构设计。
