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首页> 外文期刊>The Journal of Prosthetic Dentistry >The influence of veneering porcelain thickness of all-ceramic and metal ceramic crowns on failure resistance after cyclic loading.
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The influence of veneering porcelain thickness of all-ceramic and metal ceramic crowns on failure resistance after cyclic loading.

机译：全瓷和金属陶瓷冠的饰面瓷厚度对循环载荷后抗破坏性的影响。

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STATEMENT OF PROBLEM: In some clinical situations, the length of either a prepared tooth or an implant abutment is shorter than ideal, and the thickness of a porcelain crown must be increased. Thickness of the coping and the veneering porcelain should be considered to prevent mechanical failure of the crown. PURPOSE: The purpose of this study was to investigate the influence of veneering porcelain thickness for all-ceramic and metal ceramic crowns on failure resistance after cyclic loading. MATERIAL AND METHODS: All-ceramic and metal ceramic crowns (n=20) were fabricated on an implant abutment (RN Solid Abutment) for the study. Two different framework designs with 2 different incisal thicknesses of veneering porcelain (2 mm and 4 mm) were used for each all-ceramic and metal ceramic crown system, resulting in 4 experimental groups (n=10) with identically shaped crowns. The all-ceramic crown consisted of alumina (Procera AllCeram) frameworks and veneering porcelain (Cerabien), while metal ceramic crowns were made of high noble metal (Leo) frameworks and veneering porcelain (IPS Classic). All crowns were cemented on the corresponding abutments using a resin cement (Panavia 21). They were subjected to 1000 cycles of thermal cycling (5 degrees C and 55 degrees C; 5-second dwell time). The crowns were tested with a custom-designed cyclic loading apparatus which delivered simultaneous unidirectional cyclic loading at 135 degrees, vertically, at an rpm of 250, with a load of 49 N. Each specimen was loaded for 1.2 x 106 cycles or until it failed. The specimens were thoroughly evaluated for cracks and/or bulk fracture with an optical stereomicroscope (x10) and assigned a score of success, survival, or failure. The specimens without bulk fracture after cyclic loading were loaded along the long axis of the tooth, on the incisal edge, in a universal testing machine at a crosshead speed of 1.5 mm/min, until fracture. Fisher's exact test was used to compare the success and survival rate between the 2 different materials (alpha=.05). Two-way ANOVA was used to analyze data in terms of material, porcelain thickness, and interaction effect. Also, a 2-sample t test was performed to compare between 2 thicknesses within the same material (alpha=.05). RESULTS: According to the Fisher's exact test, the all-ceramic group showed significantly higher success (P=.003) and survival rates (P=.001) than the metal ceramic group. For the failure load, the 2-way ANOVA showed significant effects for material (P<.001) and porcelain thickness (P=.004), but not a significant interaction effect (P=.198). For the metal ceramic groups, crowns with a 2-mm porcelain thickness showed a significantly greater failure load than crowns with a 4-mm porcelain thickness (P=.004). However, all-ceramic groups did not show a significant difference between the 2 different thicknesses of veneering porcelain (P=.198). CONCLUSIONS: The all-ceramic crowns showed significantly higher success and survival rates after cyclic loading, but lower failure loads than metal ceramic crowns. The thickness of the veneering porcelain affected the failure load of the metal ceramic crowns, but not that of the all-ceramic crowns.
机译：问题陈述：在某些临床情况下，准备好的牙齿或种植体基台的长度比理想的短，并且必须增加瓷冠的厚度。应考虑顶盖和饰面瓷的厚度，以防止表冠发生机械故障。目的：本研究的目的是研究全瓷和金属陶瓷冠的饰面瓷厚度对循环载荷后抗破坏性的影响。材料与方法：全陶瓷和金属陶瓷牙冠（n = 20）均在种植体基台（RN Solid Abutment）上制造，用于研究。对于每种全陶瓷和金属陶瓷冠系统，使用两种不同的框架设计，分别使用2种不同切面厚度的饰面瓷（2 mm和4 mm），形成4个具有相同形状冠的实验组（n = 10）。全瓷冠由氧化铝（Procera AllCeram）骨架和饰面瓷（Cerabien）组成，而金属陶瓷冠则由高贵金属（Leo）骨架和饰面瓷（IPS Classic）制成。使用树脂胶粘剂（Panavia 21）将所有牙冠粘在相应的基台上。他们经历了1000次热循环（5摄氏度和55摄氏度; 5秒的停留时间）。使用定制设计的循环加载设备测试牙冠，该设备在135度，垂直，250 rpm，49 N的载荷下同时进行单向循环载荷。每个样本均进行1.2 x 106循环的加载或直至失败。使用光学体视显微镜（x10）对样品进行了裂纹和/或整体断裂的彻底评估，并指定了成功，存活或失败的评分。在万能试验机中，以1.5 mm / min的十字头速度，在循环载荷后将没有大块断裂的试样沿着牙齿的长轴切入边缘沿牙齿的长轴加载，直到断裂。 Fisher精确检验用于比较两种不同材料之间的成功率和存活率（alpha = .05）。双向方差分析用于分析材料，瓷器厚度和相互作用效应方面的数据。此外，还进行了2个样本的t检验，以比较同一材料内的2个厚度（α= .05）。结果：根据Fisher的精确测试，全陶瓷组的成功率（P = .003）和存活率（P = .001）均比金属陶瓷组高。对于破坏载荷，两向方差分析对材料（P <.001）和瓷器厚度（P = .004）表现出显着影响，但对交互作用的影响则不显着（P = .198）。对于金属陶瓷组，具有2mm瓷厚的牙冠比具有4mm瓷厚的牙冠显示出更大的失效载荷（P = .004）。但是，全陶瓷组在两种不同厚度的饰面瓷之间没有显示出显着差异（P = .198）。结论：全陶瓷牙冠在循环载荷后显示出更高的成功率和存活率，但比金属陶瓷牙冠具有更低的破坏载荷。饰面瓷的厚度影响金属陶瓷冠的破坏载荷，但不影响全陶瓷冠的破坏载荷。

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