This study evaluated the effect of grinding and regeneration firing on the flexural fatigue limit and surface characterization of Lava™ Y-TZP ceramic. Forty bar-shaped specimens with 20 × 4.0 × 1.2 mm constituted the as-sintered group (AS = control group), and 80 specimens with 20 × 4.0 × 1.5 mm were ground with cylindrical laboratory stone under water-cooling (WG) or in a dry condition (G) to reach 1.2 mm in thickness. Half of specimens were submitted to regeneration firing (1000 °C, 30 min), forming the groups AS/R, WG/R and G/R. Fatigue limit (500,000 cycles, 10 Hz) was determined by staircase method in a 4-point flexural fixture. Data were analyzed by 2-way ANOVA and Tukey HSD tests (α = 0.05). The surface topography (n = 3) and fracture area (n = 3) were evaluated by SEM. Samples were also analyzed by Rietveld refinement from X-ray diffraction data. ANOVA revealed significant differences (P < .001) for grinding protocol, regeneration firing and their interaction. In the groups not submitted to regeneration firing, the mean flexural fatigue limit of WG was higher (P < .05) than that of G and AS, with no statistical difference between each other (P > .05). After regeneration firing the inequality WG>AS>G (P < .05) was observed. The regeneration firing increased the fatigue limit of AS group and decreased those of G and WG groups (P < .05). Grinding protocols created evident grooves on zirconia surface. Failures initiated on tensile side of all specimens. The percentages (wt%) of monoclinic phase before cyclic loading were: AS (7.4), AS/R (6.5), G (2.8), G/R (0.0), WG (4.4), WG/R (0.0); and after cyclic loading: AS (8.6), AS/R (1.2), G (2.4), G/R (5.7), WG (6.3), WG/R (0.0). Wet grinding did not compromise the fatigue limit of zirconia, increasing its mechanical strength. Regeneration firing reduced the fatigue limit of ground samples, despite reducing the amount of monoclinic phase in all experimental conditions.

这项研究评估了研磨和再生烧成对Lava™Y-TZP陶瓷的弯曲疲劳极限和表面特性的影响。将40个20×4.0×1.2 mm的棒状样本作为烧结组（AS =对照组），并将80×20×4.0×1.5 mm的样本在水冷（WG）或以下条件下用圆柱形实验室石磨碎。干燥条件（G）达到1.2毫米的厚度。一半标本经过再生烧制（1000°C，30分钟），形成AS / R，WG / R和G / R组。在四点弯曲夹具中通过阶梯法确定疲劳极限（500,000个循环，10 Hz）。数据通过2通ANOVA和Tukey HSD测试进行分析（α= 0.05）。通过SEM评价表面形貌（n ＝ 3）和断裂面积（n ＝ 3）。还通过Rietveld精修从X射线衍射数据分析了样品。方差分析显示，研磨方案，再生烧结及其相互作用存在显着差异（P <0.001）。在未接受再生击发的组中，WG的平均弯曲疲劳极限值高于（P <.05），高于G和AS的平均值，彼此之间无统计学差异（P> .05）。再生后，不等式WG > AS > G（P ＜.05）被观察到。再生点火提高了AS组的疲劳极限，降低了G组和WG组的疲劳极限（P <.05）。研磨方案在氧化锆表面上形成明显的凹槽。失效始于所有试样的拉伸侧。循环加载前单斜晶相的百分比（wt％）为：AS（7.4），AS / R（6.5），G（2.8），G / R（0.0），WG（4.4），WG / R（0.0）；循环加载后：AS（8.6），AS / R（1.2），G（2.4），G / R（5.7），WG（6.3），WG / R（0.0）。湿磨并未损害氧化锆的疲劳极限，从而提高了其机械强度。尽管减少了所有实验条件下的单斜晶相数量，但再生燃烧降低了地面样品的疲劳极限。