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A Finite Element Approach for Locating the Center of Resistance of Maxillary Teeth.

上颌牙齿阻力中心定位的有限元方法。

  • 影响因子:1.30
  • DOI:10.3791/60746
  • 作者列表:"Luu B","Cronauer EA","Gandhi V","Kaplan J","Pierce DM","Upadhyay M
  • 发表时间:2020-04-08
Abstract

:The center of resistance (CRES) is regarded as the fundamental reference point for predictable tooth movement. The methods used to estimate the CRES of teeth range from traditional radiographic and physical measurements to in vitro analysis on models or cadaver specimens. Techniques involving finite element analysis of high-dose micro-CT scans of models and single teeth have shown a lot of promise, but little has been done with newer, low-dose, and low resolution cone beam computed tomography (CBCT) images. Also, the CRES for only a few select teeth (i.e., maxillary central incisor, canine, and first molar) have been described; the rest have been largely ignored. There is also a need to describe the methodology of determining the CRES in detail, so that it becomes easy to replicate and build upon. This study used routine CBCT patient images for developing tools and a workflow to obtain finite element models for locating the CRES of maxillary teeth. The CBCT volume images were manipulated to extract three-dimensional (3D) biological structures relevant in determining the CRES of the maxillary teeth by segmentation. The segmented objects were cleaned and converted into a virtual mesh made up tetrahedral (tet4) triangles having a maximum edge length of 1 mm with 3matic software. The models were further converted into a solid volumetric mesh of tetrahedrons with a maximum edge length of 1 mm for use in finite element analysis. The engineering software, Abaqus, was used to preprocess the models to create an assembly and set material properties, interaction conditions, boundary conditions, and load applications. The loads, when analyzed, simulated the stresses and strains on the system, aiding in locating the CRES. This study is the first step in accurate prediction of tooth movement.

摘要

: 阻力中心 (CRES) 被认为是可预测牙齿移动的基本参考点。用于估计牙齿CRES的方法范围从传统的射线照相和物理测量到模型或尸体标本的体外分析。涉及模型和单个牙齿的高剂量微CT扫描的有限元分析的技术已经显示出很多希望,但是对于更新的、低剂量和低分辨率的锥形束计算机断层扫描 (CBCT) 图像几乎没有做。此外,仅描述了少数选定牙齿 (即上颌中切牙、尖牙和第一磨牙) 的CRES; 其余的在很大程度上被忽略。还需要详细描述确定CRES的方法,以便易于复制和构建。本研究使用常规CBCT患者图像开发工具和工作流程,以获得用于定位上颌牙齿CRES的有限元模型。操纵CBCT体积图像以提取与通过分割确定上颌牙齿的CRES相关的三维 (3D) 生物结构。用3个matic软件将分割的对象清洁并转换成由具有1毫米mm的最大边缘长度的四面体 (tet4) 三角形构成的虚拟网格。将模型进一步转换为四面体的实体体积网格,最大边缘长度为1毫米mm,用于有限元分析。使用工程软件Abaqus对模型进行预处理,以创建组件并设置材料属性、相互作用条件、边界条件和载荷应用。分析时,载荷模拟了系统上的应力和应变,有助于定位CRES。本研究是准确预测牙齿移动的第一步。

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作者列表:["Delattre BMA","Boudabbous S","Hansen C","Neroladaki A","Hachulla AL","Vargas MI"]

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影响因子:2.98
发表时间:2020-01-01
DOI:10.1136/neurintsurg-2019-014962
作者列表:["Guo W","Liu H","Tan Z","Zhang X","Gao J","Zhang L","Guo H","Bai H","Cui W","Liu X","Wu X","Luo J","Qu Y"]

METHODS:BACKGROUND:The main surgical techniques for spontaneous basal ganglia hemorrhage include stereotactic aspiration, endoscopic aspiration, and craniotomy. However, credible evidence is still needed to validate the effect of these techniques. OBJECTIVE:To explore the long-term outcomes of the three surgical techniques in the treatment of spontaneous basal ganglia hemorrhage. METHODS:Five hundred and sixteen patients with spontaneous basal ganglia hemorrhage who received stereotactic aspiration, endoscopic aspiration, or craniotomy were reviewed retrospectively. Six-month mortality and the modified Rankin Scale score were the primary and secondary outcomes, respectively. A multivariate logistic regression model was used to assess the effects of different surgical techniques on patient outcomes. RESULTS:For the entire cohort, the 6-month mortality in the endoscopic aspiration group was significantly lower than that in the stereotactic aspiration group (odds ratio (OR) 4.280, 95% CI 2.186 to 8.380); the 6-month mortality in the endoscopic aspiration group was lower than that in the craniotomy group, but the difference was not significant (OR=1.930, 95% CI 0.835 to 4.465). A further subgroup analysis was stratified by hematoma volume. The mortality in the endoscopic aspiration group was significantly lower than in the stereotactic aspiration group in the medium (≥40-<80 mL) (OR=2.438, 95% CI 1.101 to 5.402) and large hematoma subgroup (≥80 mL) (OR=66.532, 95% CI 6.345 to 697.675). Compared with the endoscopic aspiration group, a trend towards increased mortality was observed in the large hematoma subgroup of the craniotomy group (OR=8.721, 95% CI 0.933 to 81.551). CONCLUSION:Endoscopic aspiration can decrease the 6-month mortality of spontaneous basal ganglia hemorrhage, especially in patients with a hematoma volume ≥40 mL.

影响因子:0.96
发表时间:2020-02-01
DOI:10.1002/jcu.22762
作者列表:["Meng L","Zhao D","Yang Z","Wang B"]

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