Rosentritt Martin, Behr Michael, van der Zel Jef M, Feilzer Albert J
Department of Prosthetic Dentistry, Regensburg University Medical Center, Regensburg, Germany.
Dent Mater. 2009 Mar;25(3):348-52. doi: 10.1016/j.dental.2008.08.009. Epub 2008 Oct 1.
The aim of this investigation was to determine the fracture resistance of zirconia fixed partial dentures (FPDs) after laboratory simulation. Failure type and failure rates during simulation were compared to available clinical data for estimating the relevance of the simulation.
32 FPDs were fabricated of a zirconia ceramic and a corresponding ceramic veneer. The FPDs were adhesively bonded on human molars and artificial aging was performed for investigating the survival rate during thermal cycling and mechanical loading (TCML1; 3.6Mio x 50N ML). Survival rates were compared to available clinical data and the TCML parameter "mastication force" was adapted accordingly for a second TCML run (TCML2; 3.6Mio x 100N ML). The fracture resistance of the FPDs which survived TCML was determined. FPDs were examined without TCML (control) or after TCML according to literature (1.2Mio x 50N ML). Data were statistically analyzed (Mann-Whitney U-test) and curve fitting/regression analysis of the survival rates was performed.
TCML reduced survival rates down to 63%. Failures during TCML were chipping off of the veneering ceramic, no zirconia framework was damaged. Under clinical conditions comparable failures (chipping) are reported. The clinical survival rate (approximately 10%) is lower compared to TCML data because of the short period of observation. The fracture resistance after TCML was significantly reduced from 1058N (control) to values between 320 and 533N.
The results indicate that TCML with 1.2Mio x 50N provides a sufficient explanatory power. TCML with prolonged simulation time may allow the definition of a mathematical model for estimating future survival rates.
本研究旨在确定经过实验室模拟后氧化锆固定局部义齿（FPDs）的抗折性。将模拟过程中的失败类型和失败率与现有的临床数据进行比较，以评估模拟的相关性。
用氧化锆陶瓷和相应的陶瓷贴面制作32个FPDs。将FPDs粘结在人类磨牙上，并进行人工老化处理，以研究其在热循环和机械加载（TCML1；360万次×50N加载）过程中的存活率。将存活率与现有的临床数据进行比较，并相应调整TCML参数“咀嚼力”，进行第二次TCML实验（TCML2；360万次×100N加载）。测定在TCML实验后存活的FPDs的抗折性。根据文献，对未进行TCML实验（对照组）或经过TCML实验（120万次×50N加载）后的FPDs进行检查。对数据进行统计分析（曼-惠特尼U检验），并对存活率进行曲线拟合/回归分析。
TCML使存活率降至63%。TCML实验中的失败表现为贴面陶瓷剥落，氧化锆支架未受损。据报道，在临床条件下也有类似的失败情况（剥落）。由于观察期较短，临床存活率（约10%）低于TCML实验数据。TCML实验后的抗折性从1058N（对照组）显著降低至320至533N之间。
结果表明，120万次×50N的TCML实验具有足够的解释力。延长模拟时间的TCML实验可能有助于定义一个用于估计未来存活率的数学模型。
