The influence of low-temperature degradation and cyclic loading on the fracture resistance of monolithic zirconia molar crowns
The influence of low-temperature degradation and cyclic loading on the fracture resistance of monolithic zirconia molar crowns
复制标题
DOI：
10.1016/j.jmbbm.2015.03.007
复制
发表时间：
2015-07-01
影响因子：
3.9
通讯作者：
Ortengren, U.
中科院分区：
文献类型：
--
作者：
Nakamura, K.;Harada, A.;Ortengren, U.
本研究分析了氧化锆低温降解的动力学，并评价了低温降解和循环载荷对氧化锆磨牙全冠抗断裂性能的影响。将棒形氧化锆试样分为9组，并在134 ℃下高压灭菌0-200 h以诱导LTD。使用X射线衍射和扫描电子显微镜检查单斜相的表面分数和穿透深度。制备氧化锆单块磨牙全冠，进行冠折试验。将冠高压灭菌0-100 h（n=6）并粘固到模具上。对6个未经高压灭菌的冠模样品和6个高压灭菌100 h的样品进行240，000次循环，载荷为300 N。所有样品均在失效载荷测试中进行测试。表面的单斜相分数随压热时间的增加而增加，在50 h后达到一个平台。单斜相的深度增加而没有达到平台。高压灭菌100 h后，冠的断裂载荷从5683 N（SD：342）降至3975 N（SD：194）。在所有情况下，循环载荷并没有显着影响冠的抗断裂性。动力学分析表明，在50小时的高压灭菌后，表面分数和单斜相的深度之间没有线性相关性。即使LTD增加了单斜相，导致强度较低，但整体氧化锆冠的抗断裂性仍足以承受磨牙区的载荷条件。(C)2015爱思唯尔有限公司版权所有。
The present study analyzed the kinetics of low-temperature degradation (LTD) in zirconia, and evaluated the influence of LTD and cyclic loading on the fracture resistance of monolithic zirconia molar crowns. Bar-shaped zirconia specimens were divided into nine groups and autoclaved at 134 degrees C for 0-200 h to induce LTD. The surface fraction and penetration depth of the monoclinic phase were examined using X-ray diffraction and scanning electron microscopy. Monolithic zirconia molar crowns were prepared for crown fracture testing. The crowns were autoclaved for 0-100 h (n=6) and cemented to dies. Six crown-die samples that were not autoclaved and six samples that were autoclaved for 100 h were subjected to cyclic loading with a load of 300 N for 240,000 cycles. All samples were tested in a load-to-failure test. The monoclinic fraction on the surface increased with autoclaving time and reached a plateau after 50 h. The depth of the monoclinic phase increased without reaching a plateau. The fracture load of the crowns significantly decreased from 5683 N (SD: 342) to 3975 N (SD: 194) after 100 h of autoclaving. Cyclic loading did not significantly affect the fracture resistance of the crowns in all cases. Kinetic analysis showed no linear correlation between the surface fraction and depth of the monoclinic phase after 50 h of autoclaving. Even though LTD increased the monoclinic phase, resulting in lower strength, the fracture resistance of the monolithic zirconia crowns was still sufficient to withstand the loading conditions in the molar regions. (C) 2015 Elsevier Ltd. All rights reserved.