Fracture Characteristics of Dental Ceramic Crown according to Zirconia Coping Design
Fracture Characteristics of Dental Ceramic Crown according to Zirconia Coping Design
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根据氧化锆内冠设计的牙科陶瓷冠的断裂特性
DOI：
10.1016/j.proeng.2011.04.261
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
M. Son
中科院分区：
文献类型：
--
作者：
H. Cho;H. Y. Won;H. Choe;M. Son
采用不同的实验方法，研究了氧化锆陶瓷冠的断裂特征。用光学扫描仪（S600，Zirkonzahn，意大利）扫描下颌第一磨牙丙烯酸树脂模型牙的三维轮廓尺寸，然后在CAD软件（Zirkonzahn.Modellier，Zirkonzahn，意大利）中创建一个经典的冠制备。将准备好的牙齿的CAD文件导入铣床，并生成丙烯酸树脂（PMMA）模具。根据氧化锆边缘领的厚度，使用四种不同的内冠设计：0.0mm氧化锆领（组1），0.5mm（组2），1.0mm（组3）和2.0mm（组4）。采用CAD/CAM系统（CAD CAM M5，Zirkonzahn，意大利）制作冠，采用分层技术制作贴面瓷（IPS e.max Ceram）。将所有样品粘合（RelyX Unicem，3 M/ESPE）到相应的模具上。根据氧化锆颈领的厚度，将所有样本分为4组（每组n=10）进行测试。对每组8个冠进行断裂载荷试验，其余2个冠进行疲劳试验。用万能试验机以1.0mm/min的十字头速度测试断裂强度。对于疲劳失效测试，样本以15 Hz的速率经受50，000次200 N的循环载荷循环，然后以1.0 mm/min的十字头速度动态加载，直至失效。用场发射扫描电子显微镜（FE-SEM S-4800，Hitachi，Japan）观察失败冠的断裂位置和断裂表面。贴面瓷的断裂强度平均值为：组1为1411 N，组2为1428 N，组3为1596 N，组4为1621 N。随着瓷冠厚度的增加，氧化锆冠的断裂强度值也随着瓷冠的断裂强度的增加而增加。通过FE-SEM观察，从断口上可以看出两种有趣的特征，即突然断裂和渐进断裂。试件的破坏主要是由饰面瓷内部的孔隙引发的裂纹扩展引起的。根据断裂试验可知，氧化锆领的厚度越大，贴面瓷的断裂强度越高。因此，对于氧化锆-陶瓷修复体的功能寿命和美学而言，推荐使用边缘领宽度为2.0mm的氧化锆顶盖设计。
Fracture characteristics of the ceramic crown according to the zirconia coping design have been researched using various experimental methods. The 3D contour dimension of a mandibular first molar acrylic model tooth was scanned with Optical scanner (S600, Zirkonzahn, Italy), and then a classic crown preparation was created in CAD software (Zirkonzahn.Modellier, Zirkonzahn, Italy). The CAD file of the prepared tooth was imported into a milling machine, and acrylic resin (PMMA) dies were generated. Four different coping designs based on the thickness of zirconia marginal collar were used: 0.0mm zirconia collar (Group1), 0.5mm (Group2), 1.0mm (Group3), and 2.0mm (Group4). Copings were fabricated with CAD/CAM System (CAD CAM M5, Zirkonzahn, Italy) and veneering porcelain (IPS e.max Ceram) was build-up with layering technique. All the samples were cemented (RelyX Unicem, 3M/ESPE) onto corresponding dies. All specimens were tested in 4 groups (n=10 for each group) based on the thickness of zirconia collar. Fracture load test was performed on eight crowns from each group, and the remaining crowns (n=2) were subjected to fatigue test. Fracture strength was tested with a universal testing machine at a crosshead speed of 1.0mm/min to the vertical axis of the tooth 0.5mm lingually down the mesio-distal cusp. For the testing of fatigue failure, specimens were subjected to 50,000 cycles of cyclic loading 200N, at a rate of 15Hz and then loaded dynamically at a crosshead speed of 1.0mm/min, until failure. Fracture location and fracture surface of failed crowns were observed with a field emission scanning electron microscope (FE-SEM S-4800, Hitachi, Japan). Mean of fracture strength values of veneering porcelain were: 1411N for Group1, 1428N for Group2, 1596N for Group3 and 1621N for Group4. And according to increasing of thickness on zirconia collar, zirconia coping showed more fracture strength value with increasing of fracture strength of porcelain veneered it up. And examined using FE-SEM, two interesting features were shown from the fracture surface, sudden fracture and gradual fracture. And failure of specimens was mainly occurred by crack growth initiated from porosities within the veneering porcelain. In conclusion, according to the fracture test, the more thickness of zirconia collar, the higher fracture strength of veneering porcelain. Thus, zirconia coping design with 2.0mm marginal collar width is recommended for both functional longevity and esthetics of zirconia-ceramic restoration.