The aim of the study was to compare the outcomes for the fatigue mechanical behavior of bonded simplified lithium disilicate restorations, with and without an internal adjustment by grinding with diamond bur in running two fatigue tests: Staircase and Step-stress testing approaches. Ceramic discs (IPS e.max CAD) were prepared (Ø = 10 mm; thickness = 1.0 mm), submitted to an in-lab simulation of CAD/CAM milling (#60 SiC paper) and allocated into 2 groups according to the internal adjustment by grinding of the cementation surface: no adjustment (CTRL); or grinding with a coarse diamond bur (GR). Adhesive cementation (Multilink N) was performed onto epoxy resin discs (Ø = 10 mm; thickness = 2 mm) after ceramic/epoxy surface treatments. The cemented assemblies of each group were randomly assigned into 2 subgroups considering two fatigue tests (n = 15): Staircase – SC (250,000 cycles; 20 Hz), or Step-stress – SS (10,000 cycles per step; 20 Hz). Roughness, topographic and fractographic analyses were additionally performed. Statistical analyses were carried out using the Dixon and Mood method for Staircase data, and Kaplan–Meier and Mantel-Cox (log-rank) tests for Step-stress data. Ceramic restorations having its intaglio surface ground (GR group: SC test = 306.67 N; SS test = 646.67 N) presented lower fatigue failure load (FFL) values than the CTRL group (SC test = 879.28 N; SS test = 1090.00 N), regardless of the fatigue testing approach. The percentage of mean FFL decrease comparing the CTRL to GR group was higher for SC (65.1%) than the SS (40.7%) approach. However, a different total number of cycles was applied for each method. Both fatigue tests were able to detect the negative effect of internal adjustments of lithium disilicate glass-ceramic simplified restorations on their mechanical behavior. Therefore, both methods can be applied for similar evaluations (fatigue testing for ceramic restorations).

该研究的目的是比较在进行两种疲劳测试（楼梯和阶梯应力测试方法）时，结合和不结合通过金刚石钻头磨削进行内部调整的情况，粘合的简化二硅酸锂修复体的疲劳力学性能结果。制备陶瓷圆盘（IPS e.max CAD）（Ø= 10 mm；厚度= 1.0 mm），进行CAD / CAM铣削的实验室内模拟（＃60 SiC纸），并根据内部情况分为2组通过研磨胶结表面进行调整：不调整（CTRL）；或用粗金刚石车针（GR）研磨。陶瓷/环氧树脂表面处理后，在环氧树脂圆盘（Ø= 10毫米；厚度= 2毫米）上进行粘合胶结（Multilink N）。考虑到两个疲劳测试（n = 15），将每组胶合组件随机分为2个子组：楼梯– SC（250,000个周期； 20 Hz），或阶梯应力– SS（10,000个周期/步； 20 Hz）。另外进行粗糙度，形貌和分形分析。使用Dixon和Mood方法对楼梯数据进行统计分析，并使用Kaplan–Meier和Mantel-Cox（对数秩）检验进行阶梯应力数据进行统计分析。带有凹版表面的陶瓷修复体（GR组：SC测试= 306.67 N； SS测试= 646.67 N）比CTRL组（SC测试= 879.28 N； SS测试= 1090.00 N）具有更低的疲劳破坏载荷（FFL）值，不论疲劳测试方法如何。与CTRL和GR组相比，SC组的平均FFL降低百分比（65.1％）高于SS组（40.7％）。但是，每种方法的总循环数不同。两种疲劳测试均能够检测到内部调整的二硅酸锂玻璃-陶瓷简化修复体对其机械性能的负面影响。因此，这两种方法都可以用于类似的评估（陶瓷修复体的疲劳测试）。