Department of Restorative Dentistry, Columbia University, College of Dental Medicine, New York, NY, USA.
J Prosthet Dent. 2013 Apr;109(4):234-40. doi: 10.1016/S0022-3913(13)60051-7.
Veneering ceramic materials designed to be used with high noble alloy and zirconia-based restorations have been reported to be susceptible to chipping in vivo.
The purpose of this study was to evaluate and compare the fracture toughness of heat-pressed and layered ceramics intended for zirconia and high-noble alloy substrates.
Bar specimens were fabricated from 8 different ceramics (Ivoclar-Vivadent [I] and Noritake [N]) intended for pressing (P) and layering (L) to high noble alloy (M) and zirconia (Z) substrates, following the ISO 6872 protocol. The single edge notch beam test method was used to create a notch in the center of each specimen, which was then tested with a universal testing machine (n=6, cross-head speed=0.5 mm/min) and the fracture force values recorded. These values were used to calculate the fracture toughness (K1c) for each specimen. Fracture surfaces were examined with a scanning electron microscope, and the basic components of the tested ceramics were determined by using energy dispersive x-ray (EDX) spectroscopy. Data were analyzed with 3-way ANOVA, followed by multiple comparisons using the Holm method (α=.05).
The mean (SD) of the calculated fracture toughness values obtained ranged from 1.20 (0.04) MPa·m(1/2) (group NZL) to 1.74 (0.04) MPa·m(1/2) (group IZL). Fracture toughness was significantly higher in group IZL (1.74) than group IZP (1.41), but lower in group NZL (1.20) than group NZP (1.36) (P<.001). Fracture toughness was somewhat lower in group IML (1.36) than group IMP (1.47) (P=.018), and no significant difference was found between group NML and group NMP (P=.14). Veneering ceramics used with a metal substrate showed a crystalline structure mixed with a glassy phase pattern on the fracture surface. The results of EDX analysis on the fracture surfaces indicated that the tested ceramics were composed of Si, Al, K, Na, Mg, and oxygen elements.
Ceramics used for veneering zirconia substrate may have various fracture toughness values that relate primarily to the processing technique.
用于高贵金属合金和氧化锆修复体的贴面陶瓷材料据报道在体内易出现崩瓷。
本研究的目的是评估和比较用于氧化锆和高贵金属合金基底的热压和分层陶瓷的断裂韧性。
根据 ISO 6872 协议，从 8 种不同的陶瓷（义获嘉[I]和则武[N]）中制作用于热压（P）和分层（L）的棒状试件，分别用于高贵金属合金（M）和氧化锆（Z）基底。采用单边切口梁试验法在每个试件的中心处制造切口，然后用万能试验机（n=6，十字头速度=0.5mm/min）进行测试并记录断裂力值。根据这些值计算每个试件的断裂韧性（K1c）。用扫描电子显微镜检查断裂面，并通过能量色散 X 射线（EDX）光谱确定测试陶瓷的基本成分。采用 3 因素方差分析数据，然后采用 Holm 方法（α=.05）进行多重比较。
计算得到的断裂韧性值的平均值（标准差）范围为 1.20（0.04）MPa·m(1/2)（NZL 组）至 1.74（0.04）MPa·m(1/2)（IZL 组）。IZL 组（1.74）的断裂韧性明显高于 IZP 组（1.41），但 NZL 组（1.20）的断裂韧性低于 NZP 组（1.36）（P<.001）。IZM 组（1.36）的断裂韧性略低于 IPM 组（1.47）（P=.018），而 NML 组和 NMP 组之间无显著性差异（P=.14）。用于金属基底的贴面陶瓷在断裂面上显示出混合有玻璃相图案的结晶结构。对断裂面的 EDX 分析结果表明，测试陶瓷由 Si、Al、K、Na、Mg 和氧元素组成。
用于氧化锆基底的贴面陶瓷可能具有各种断裂韧性值，主要与加工技术有关。
