Department of Biomaterials and Oral Biochemistry, School of Dentistry, University of São Paulo, São Paulo, Brazil.
Dent Mater. 2011 Apr;27(4):394-406. doi: 10.1016/j.dental.2010.10.025. Epub 2010 Dec 24.
To determine the slow crack growth (SCG) and Weibull parameters of five dental ceramics: a vitreous porcelain (V), a leucite-based porcelain (D), a leucite-based glass-ceramic (E1), a lithium disilicate glass-ceramic (E2) and a glass-infiltrated alumina composite (IC).
Eighty disks (Ø 12 mm × 1.1mm thick) of each material were constructed according to manufacturers' recommendations and polished. The stress corrosion susceptibility coefficient (n) was obtained by dynamic fatigue test, and specimens were tested in biaxial flexure at five stress rates immersed in artificial saliva at 37 °C. Weibull parameters were calculated for the 30 specimens tested at 1 MPa/s in artificial saliva at 37 °C. The 80 specimens were distributed as follows: 10 for each stress rate (10(-2), 10(-1), 10(1), 10(2)MPa/s), 10 for inert strength (10(2)MPa/s, silicon oil) and 30 for 10(0)MPa/s. Fractographic analysis was also performed to investigate the fracture origin.
E2 showed the lowest slow crack growth susceptibility coefficient (17.2), followed by D (20.4) and V (26.3). E1 and IC presented the highest n values (30.1 and 31.1, respectively). Porcelain V presented the lowest Weibull modulus (5.2). All other materials showed similar Weibull modulus values, ranging from 9.4 to 11.7. Fractographic analysis indicated that for porcelain D, glass-ceramics E1 and E2, and composite IC crack deflection was the main toughening mechanism.
This study provides a detailed microstructural and slow crack growth characterization of widely used dental ceramics. This is important from a clinical standpoint to assist the clinician in choosing the best ceramic material for each situation as well as predicting its clinical longevity. It also can be helpful in developing new materials for dental prostheses.
确定五种牙科陶瓷的慢裂纹扩展（SCG）和威布尔参数：一种玻璃质瓷（V）、一种透锂长石瓷（D）、一种透锂长石玻璃陶瓷（E1）、一种锂硅玻璃陶瓷（E2）和一种玻璃渗透氧化铝复合材料（IC）。
根据制造商的建议，构建了 80 个（Ø 12mm×1.1mm 厚）每种材料的圆盘，并对其进行抛光。通过动态疲劳试验获得应力腐蚀敏感性系数（n），并在 37°C 下人工唾液中以五个应力速率对试件进行双轴弯曲测试。在 37°C 下的人工唾液中以 1MPa/s 的速率测试 30 个试件，计算威布尔参数。80 个试件的分布如下：10 个用于每个应力速率（10(-2)、10(-1)、10(1)、10(2)MPa/s），10 个用于惰性强度（10(2)MPa/s，硅油），30 个用于 10(0)MPa/s。还进行了断口分析，以研究断裂起源。
E2 表现出最低的慢裂纹扩展敏感性系数（17.2），其次是 D（20.4）和 V（26.3）。E1 和 IC 呈现出最高的 n 值（30.1 和 31.1）。瓷 V 呈现出最低的威布尔模数（5.2）。所有其他材料的威布尔模数值相似，范围在 9.4 到 11.7 之间。断口分析表明，对于瓷 D、玻璃陶瓷 E1 和 E2 以及复合材料 IC，裂纹偏转是主要的增韧机制。
本研究对广泛使用的牙科陶瓷进行了详细的微观结构和慢裂纹扩展特性分析。从临床角度来看，这一点很重要，有助于临床医生为每种情况选择最佳的陶瓷材料，并预测其临床寿命。它也可以帮助开发用于牙科修复体的新材料。
