Department of Dental Materials and Restorative Dentistry, University of Uberaba, Uberaba, Brazil.
J Prosthodont. 2009 Dec;18(8):649-55. doi: 10.1111/j.1532-849X.2009.00498.x. Epub 2009 Aug 4.
The aim of this study was to test the hypothesis that fracture loads of fatigued dental ceramic crowns are affected by testing environment and luting cement.
One hundred and eighty crowns were prepared from bovine teeth using a lathe. Ceramic crowns were prepared from three types of ceramic systems: an alumina-infiltrated ceramic, a lithia-disilicate-based glass ceramic, and a leucite-reinforced ceramic. For each ceramic system, 30 crowns were cemented with a composite resin cement, and the remaining 30 with a resin-modified glass ionomer cement. For each ceramic system and cement, ten specimens were loaded to fracture without fatiguing. A second group (n = 10) was subjected to cyclic fatigue and fracture tested in a dry environment, and a third group (n = 10) was fatigued and fractured in distilled water. The results were statistically analyzed using one-way ANOVA and Tukey HSD test.
The fracture loads of ceramic crowns decreased significantly after cyclic fatigue loading (p<or= 0.05); furthermore, fracture loads of crowns fatigued in a wet environment were statistically lower than those in a dry environment (p < 0.05). Crowns luted with a composite resin cement showed statistically greater fracture loads than those luted with a resin-modified glass ionomer cement (p<or= 0.05).
Fracture load of the three ceramic systems was found to be influenced by ceramic composition. Moreover, cement and fatigue condition influenced the fracture loads of the crown specimens evaluated in this study.
本研究旨在验证以下假设，即疲劳后牙科陶瓷冠的断裂负荷会受到测试环境和粘固剂的影响。
使用车床从牛牙上制备 180 个牙冠。陶瓷冠由三种陶瓷系统制成：氧化铝渗透陶瓷、锂硅基玻璃陶瓷和透锂长石增强陶瓷。对于每种陶瓷系统，用复合树脂粘结剂粘结 30 个牙冠，剩余的 30 个用树脂改性玻璃离子粘结剂粘结。对于每种陶瓷系统和粘结剂，有 10 个试件未经疲劳加载至断裂。第二组（n = 10）在干燥环境下进行循环疲劳和断裂测试，第三组（n = 10）在蒸馏水中进行疲劳和断裂测试。结果采用单因素方差分析和 Tukey HSD 检验进行统计学分析。
陶瓷冠在循环疲劳加载后断裂负荷显著降低（p≤0.05）；此外，在湿环境下疲劳的牙冠的断裂负荷明显低于在干燥环境下疲劳的牙冠（p<0.05）。用复合树脂粘结剂粘结的牙冠的断裂负荷明显大于用树脂改性玻璃离子粘结剂粘结的牙冠（p≤0.05）。
三种陶瓷系统的断裂负荷受到陶瓷成分的影响。此外，粘结剂和疲劳条件影响了本研究中评估的牙冠试件的断裂负荷。
