Yang X, Li R, Ye H Q, Chen H, Wang Y, Zhou Y S, Sun Y C
Department of Prosthodontics, Peking University School and Hospital of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China.
Center for Digital Dentistry, Peking University School and Hospital of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2021 Mar 1;53(2):402-405. doi: 10.19723/j.issn.1671-167X.2021.02.028.
To evaluate the effects of different edge compensation angles on the fracture strength of multilayer zirconia all-ceramic crowns and traditional uniform zirconia all-ceramic crowns.
The resin tooth preparation specimen of the mandibular first molar with a knife-edge was fabricated. A 3D digital model of the specimen was obtained by scanning it with a 3D dental model scanner. The 3D digital model was imported into computer aided design (CAD) software, and three 3D digital models of the full crown with the same surface shape are designed with the edge compensation angles of 30°, 45° and 60°, respectively. Then, the designed 3D digital model is imported into computer aided manufacturing (CAM) software. Three kinds of multilayer and homogeneous zirconia all-porcelain crowns with different edge compensation angles were fabricated, 10 each for a total of 60. The fracture load of each crown was measured under the electronic universal testing machine.
Fracture load of multilayer and uniform zirconia all-ceramic crowns, (4 322.86±610.07) N and (5 914.12±596.80) N in the 30° group, (5 264.82±883.76) N and (5 220.83±563.38) N in the 45° group and (4 900.42±345.41) N and (5 050.22±560.24) N in the 60° group, respectively. The fracture load of multi-layer zirconia all-ceramic crowns in the 30° group was significantly lower than that of homogeneous zirconia all-ceramic crowns( < 0.05); there was no statistical significance in 45° group and 60° group(>0.05). In the multi-layer zirconia all-ceramic crowns: the fracture load of the 30° group was significantly lower than that of the 45° group ( < 0.05); there was no significant difference between the 30° group and the 60° group, the 45° group and the 60° group (>0.05).In uniform zirconia full crown group: the 30° group was higher than the 45° group, the 30° group was higher than the 60° group ( < 0.05), and there was no significant difference between the 45° group and the 60° group (>0.05).
The fracture loads of three kinds of uniform and multilayer zirconia all ceramic crowns with different edge compensation angles can meet the clinical requirements. A smaller edge compensation angle is recommended when using traditional zirconia all-ceramic crowns, while 45° is recommended when using multi-layer zirconia all-ceramic crowns.
评估不同边缘补偿角度对多层氧化锆全瓷冠和传统均匀氧化锆全瓷冠断裂强度的影响。
制作下颌第一磨牙带刃边的树脂牙体预备标本。用三维牙科模型扫描仪对标本进行扫描，获得其三维数字模型。将该三维数字模型导入计算机辅助设计（CAD）软件，分别设计边缘补偿角度为30°、45°和60°的三种表面形状相同的全冠三维数字模型。然后，将设计好的三维数字模型导入计算机辅助制造（CAM）软件。制作三种不同边缘补偿角度的多层和均质氧化锆全瓷冠，每种10个，共60个。在电子万能试验机上测量每个全冠的断裂载荷。
多层和均匀氧化锆全瓷冠的断裂载荷，30°组分别为（4322.86±610.07）N和（5914.12±596.80）N，45°组分别为（5264.82±883.76）N和（5220.83±563.38）N，60°组分别为（4900.42±345.41）N和（5050.22±560.24）N。30°组多层氧化锆全瓷冠的断裂载荷显著低于均质氧化锆全瓷冠（P<0.05）；45°组和60°组无统计学意义（P>0.05）。在多层氧化锆全瓷冠中：30°组的断裂载荷显著低于45°组（P<0.05）；30°组与60°组、45°组与60°组之间无显著差异（P>0.05）。在均匀氧化锆全冠组中：30°组高于45°组，30°组高于60°组（P<0.05），45°组与60°组之间无显著差异（P>0.05）。
三种不同边缘补偿角度的均匀和多层氧化锆全瓷冠的断裂载荷均能满足临床要求。使用传统氧化锆全瓷冠时建议采用较小的边缘补偿角度，而使用多层氧化锆全瓷冠时建议采用45°。
