Wagner W C, Chu T M
School of Dentistry, The University of Michigan, Ann Arbor, USA.
J Prosthet Dent. 1996 Aug;76(2):140-4. doi: 10.1016/s0022-3913(96)90297-8.
The traditional gold and porcelain fused to metal crowns have been challenged by the esthetic all-ceramic crown materials. Only previous experience with poor mechanical properties, lack of standardized tooth preparation, and processing challenges have prevented universal acceptance of all-ceramic crowns. However, stronger and tougher ceramics and unique processing methods for ceramics have been developed in the past 20 years. In this study, three new ceramic crown core materials were tested to compare their biaxial flexural strength and indentation fracture toughness. Ten specimens of Empress, In-Ceram, and Procera AllCeram ceramics were prepared according to their manufacturers' recommendations. The results revealed significant differences in flexural strength for the three materials (p < or = 0.05). The average flexural strengths of AllCeram, In Ceram, and Empress ceramics were 687 MPa, 352 MPa, and 134 MPa respectively. There was no statistically significant difference between the fracture toughness of Procera (4.48 MPa x m1/2) and In-Ceram ceramics (4.49 MPa x m1/2); however, both ceramics had significantly higher fracture toughness (p < 0.005) than Empress ceramic (1.74 MPa x m1/2).
传统的金瓷熔附金属冠已受到全瓷冠材料美学性能的挑战。以往全瓷冠因机械性能较差、牙体预备缺乏标准化以及加工难题等因素，未能被广泛接受。然而，在过去20年里，已研发出强度更高、韧性更强的陶瓷材料以及独特的陶瓷加工方法。在本研究中，对三种新型陶瓷冠核材料进行了测试，以比较它们的双轴弯曲强度和压痕断裂韧性。按照制造商的建议制备了10个Empress、In-Ceram和Procera AllCeram陶瓷样本。结果显示，这三种材料的弯曲强度存在显著差异（p≤0.05）。AllCeram、In-Ceram和Empress陶瓷的平均弯曲强度分别为687兆帕、352兆帕和134兆帕。Procera（4.48兆帕×米1/2）和In-Ceram陶瓷（4.49兆帕×米1/2）的断裂韧性之间无统计学显著差异；然而，这两种陶瓷的断裂韧性均显著高于Empress陶瓷（1.74兆帕×米1/2）（p＜0.005）。
