Fracture Prevention of Esthetic Ceramic Crowns for Posterior Teeth

1.美容陶瓷材料的疲劳试验：用OCC制成20×5×1.5 mm的试件，将试件表面抛光至#220和#1000。强度用伺服液压机械试验机测量。#220组的弯曲强度、疲劳强度和断裂循环次数的平均值分别为40.9 Mpa、28.8 Mpa和4.31×104次循环；#1000组的平均弯曲强度、疲劳强度和断裂循环次数分别为45.4 Mpa、35.0 Mpa和3.29×104次循环。这些结果表明，与树脂复合材料相比，OCC不是易碎材料，其表面抛光是获得更大强度所必需的。美容陶瓷材料与牙科合金的复合体或复合体的疲劳试验：将口腔美容陶瓷材料与银-钯-铜-金合金或复合体(厚度为2 mm)与粘结树脂粘结剂粘接，进行疲劳试验。抗弯强度…的平均值#220-组和#1000-组的疲劳强度和疲劳强度分别为49.6 Mpa和39.3 Mpa和54.7 Mpa和44.3 Mpa。另一方面，将OCC和复合材料组合用于堆芯，#220组的强度分别为76.3 Mpa和65.5 Mpa，#1000组的强度分别为74.8 Mpa和62.2 Mpa。这些结果表明，与单一的OCC材料相比，两种复合材料的强度都有所提高，OCC材料的表面抛光对两者的强度都没有影响。3种基牙粘结剂OCC冠的耐久性试验：用人牙、金属或复合材料作为固位体，制作3种基牙，牙合平面高度2 mm，深倒角边缘宽度1 mm。分别在三种基牙上用粘接树脂粘接OCC全冠，然后用5KGF将冠加载到咬合面的断端，共100,000个循环。OCC冠在人牙、金属和复合材料上的断裂载荷分别为107kgF、192kgf和160kgf。OCC冠在人牙上的折断载荷明显低于其他两个基牙的冠。较少

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