Fracture Prevention of Esthetic Ceramic Crowns for Posterior Teeth

1.美学陶瓷材料的疲劳试验：用OCC制备用于评价试验的试样（20×5×1.5 mm），并将其表面抛光至#220和#1000。用伺服液压机械试验机测量强度。220组的弯曲强度、疲劳强度和样本断裂时的循环次数的平均值分别为40.9 MPa、28.8 MPa和4.31×10^4次循环，1000组分别为45.4 MPa、35.0 MPa和3.29×10^4次循环。这些结果表明，与树脂复合材料相比，OCC是不易破碎的材料，其表面抛光是获得更大强度的必要条件.美学陶瓷材料与牙科合金或复合材料的复合体的疲劳试验：制备OCC与银-钯-铜-金合金或复合材料之间用粘合剂树脂粘固剂连接的用于核构建的试样（厚度为2 mm），用于疲劳试验。弯曲强度平均值 关于我们 OCC和合金组合的疲劳强度对于#220组分别为49.6MPa和39.3MPa，而对于#1000组分别为54.7MPa和44.3MPa。另一方面，对于OCC和复合材料的组合用于堆芯组装，它们的强度对于#220组分别为76.3MPa和65.5MPa，对于#1000组分别为74.8MPa和62.2MPa。结果表明，两种复合材料的强度均比单一OCC材料有所提高，且OCC材料的表面抛光对两种复合材料的强度均无影响.三种基牙的骨水泥型OCC冠的耐久性测试：制备三种类型的基牙，使用人牙、金属或复合材料进行核堆积，使咬合面高度为2 mm，深倒角边缘宽度为1 mm。在3个基牙上用粘接剂粘接OCC冠，然后用5 kgf的压力将冠加载到咬合面的折裂处，共10万次。观察到的断裂载荷OCC冠人牙，金属和复合材料分别为107 kgf，192 kgf和160 kgf。人牙OCC冠的断裂载荷显著低于其他两种基牙。少

1. Fatigue tests of esthetic ceramic material : Specimens (20×5×1.5 mm) for evaluated tests were prepared by made of the OCC and their surfaces were polished to #220 and #1000. The strengths were measured with a servohydraulic mechanical testing machine. The averages of flexural strength, fatigue strength, and the number of cycles when specimens fractured were 40.9 MPa, 28.8 MPa, and 4.31×10^4 cycles for the #220-group and 45.4 MPa, 35.0 MPa, and 3.29×10^4 cycles for the #1000-group, respectively. These results suggested that the OCC was not breakable material compared with resin composite and that its surface polishing was essential to obtain greater strengths.2. Fatigue tests of the complexes of esthetic ceramic material and dental alloy or composite for core build-up : Specimens joined between the OCC and silver-palladium-copper-gold alloy or composite for core build-up (2 mm in thickness) with adhesive resin cement were prepared for fatigue tests. The averages of flexural strength … More and fatigue strength with the combination of the OCC and alloy were 49.6 MPa and 39.3 MPa for the #220-group and 54.7 MPa and 44.3 MPa for the #1000-group, respectively. On the other hand, their strengths with the combination of the OCC and composite for core build-up were 76.3 MPa and 65.5 MPa for the #220-group and 74.8 MPa and 62.2 MPa for the #1000-group, respectively. These results showed that the strengths of both complexes were improved compared with the single OCC material and that the surface polishing of the OCC material did not influenced both strengths.3. Durability tests of the cemented OCC crown on each of the three abutments : Three types of abutments were prepared with flat occlusal surface of 2 mm in height and deep-chamfer margin of 1 mm in width by use of human tooth, metal, or composite for core build-up. The OCC crowns were luted with adhesive resin cement on each of the three abutments, followed by loading crown to the fracture on the occlusal surface with 5 kgf for 100,000 cycles. The observed fractured loads of OCC crowns on human tooth, metal, and composite were 107 kgf, 192 kgf, and 160 kgf, respectively. The fractured load of the OCC crown on human tooth showed significantly lower value than that of crowns on the other two abutments. Less