Urano Shinjiro, Hotta Yasuhiro, Miyazaki Takashi, Baba Kazuyoshi
Int J Prosthodont. 2015 Mar-Apr;28(2):191-7. doi: 10.11607/ijp.4113.
Ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) has excellent fracture toughness and bending strength that could be useful for partial denture framework application. The aim of this study was to investigate the effects of three-dimensional (3D) geometry on the bending and fatigue properties of a model simulation of Ce-TZP/A clasps.
Half oval-shaped Ce-TZP/A rods were prepared in six 3D designs. Specimens were either of standard (width divided by thickness: 2.0/1.0 mm) or flat type (2.5/0.8 mm) cross-sectional areas with taper ratios of 1.0, 0.8, or 0.6. As a comparison, cobalt-chromium (Co-Cr) alloy rods of the same shape as the Ce-TZP/A standard shape rod were prepared. All specimens were subjected to the cantilever test and loaded until fracture. They were also cyclically loaded 106 times with various constant displacements, and the maximum displacement prior to fracture was determined for each specimen. Three-dimensional finite element analysis (3D FEA), simulating the cantilever test, was performed to determine the stress distribution during loading.
Specimens with the standard cross-sectional shape exhibited higher rigidity and higher fracture loads than the flat specimens by the cantilever test. In addition, lower taper ratios were consistently associated with larger displacements at fracture. Fatigue tests revealed that the maximum displacement prior to fracture of Ce-TZP/A specimens was comparable to that of Co-Cr alloy specimens. The 3D FEA showed that specimens with a taper ratio of 0.6 had the least stress concentration.
Ce-TZP/A clasp specimens with a standard cross-sectional shape and a 0.6 taper ratio exhibited the best bending properties among those tested.
二氧化铈稳定的氧化锆/氧化铝纳米复合材料（Ce-TZP/A）具有出色的断裂韧性和弯曲强度，可用于局部义齿支架应用。本研究的目的是研究三维（3D）几何形状对Ce-TZP/A卡环模型模拟的弯曲和疲劳性能的影响。
制备了六种3D设计的半椭圆形Ce-TZP/A棒。试样的横截面积为标准型（宽度除以厚度：2.0/1.0 mm）或扁平型（2.5/0.8 mm），锥度比分别为1.0、0.8或0.6。作为对比，制备了与Ce-TZP/A标准形状棒相同形状的钴铬（Co-Cr）合金棒。所有试样均进行悬臂梁试验，加载直至断裂。它们还在各种恒定位移下循环加载106次，并确定每个试样断裂前的最大位移。进行了模拟悬臂梁试验的三维有限元分析（3D FEA），以确定加载过程中的应力分布。
通过悬臂梁试验，标准横截面形状的试样比扁平试样表现出更高的刚度和更高的断裂载荷。此外，较低的锥度比始终与断裂时较大的位移相关。疲劳试验表明，Ce-TZP/A试样断裂前的最大位移与Co-Cr合金试样相当。3D FEA显示，锥度比为0.6的试样应力集中最小。
在测试的Ce-TZP/A卡环试样中，标准横截面形状和0.6锥度比的试样表现出最佳的弯曲性能。
