Huysmans M C, Van Der Varst P G, Peters M C, Plasschaert A J
Institute for Dental Clinical Research, University of Nijmegen, Netherlands.
Dent Mater. 1992 Jul;8(4):283-8. doi: 10.1016/0109-5641(92)90101-h.
In this study, data on initial failure loads of direct post and core-restored premolar teeth were analyzed using the Weibull distribution. Restorations consisted of a prefabricated titanium alloy post, and an amalgam, composite or glass cermet core buildup in human upper premolar teeth. The specimens were subjected to compressive forces until failure at angles of 10, 45 and 90 degrees to their long axis. The two- and three-parameter Weibull distributions were compared for applicability to the failure load data. For estimation of the parameters of the two-parameter distribution: sigma 0 (reference stress) and m (Weibull modulus), linear regression was used. In this distribution, it is assumed that the third parameter, sigma u (cut-off stress), equals 0. The Maximum Likelihood (MLH) method was used to estimate all three parameters. It was found that the choice of distribution has a strong influence on the estimated values and that the three-parameter distribution is best fitted for the failure loads in this study. Comparisons were made between the failure probability curves as found by MLH estimation for the different core materials and loading angles. The results indicated that the influence of loading angle on the failure mechanism was stronger than that of core material.
在本研究中，使用威布尔分布分析了直接桩核修复前磨牙的初始破坏载荷数据。修复体包括预制钛合金桩，以及人类上颌前磨牙中的汞合金、复合树脂或玻璃陶瓷核堆积。对标本施加压缩力，直至其在与长轴成10度、45度和90度角时破坏。比较了双参数和三参数威布尔分布对破坏载荷数据的适用性。对于双参数分布参数的估计：σ0（参考应力）和m（威布尔模量），使用线性回归。在该分布中，假设第三个参数σu（截止应力）等于0。使用最大似然（MLH）方法估计所有三个参数。结果发现，分布的选择对估计值有很大影响，并且三参数分布最适合本研究中的破坏载荷。对不同核材料和加载角度通过MLH估计得到的失效概率曲线进行了比较。结果表明，加载角度对破坏机制的影响强于核材料。
