Sieper Kim, Wille Sebastian, Kern Matthias
Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany.
Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany.
J Mech Behav Biomed Mater. 2017 Oct;74:342-348. doi: 10.1016/j.jmbbm.2017.06.025. Epub 2017 Jun 21.
The aim of this study was to evaluate the fracture strength of crowns made from current CAD/CAM materials. In addition the influence of crown thickness and chewing simulation on the fracture strength was evaluated.
Crowns were fabricated from lithium disilicate, zirconia reinforced lithium silicate (ZLS-ceramic) and a polymer-infiltrated ceramic-network (PICN) with an occlusal thickness of 1.0mm or 1.5mm, respectively (n=16). Crowns were cemented on composite dies. Subgroups of eight specimens were loaded with 5kg in a chewing simulator for 1,200,000 cycles with thermal cycling. Finally, all specimens were loaded until fracture in a universal testing machine. Three-way ANOVA was used to detect statistical interaction. Differences regarding the materials were tested with two-way ANOVA, following one-way ANOVA and a post-hoc Tukey's-Test.
All crowns survived the chewing simulation. The material had a significant influence on the fracture resistance (p≤0.05). Lithium disilicate achieved the highest values of fracture strength in almost all groups followed by ZLS-ceramic. PICN achieved the lowest values of fracture strength. Chewing simulation increased the fracture strength of thick lithium disilicate crown significantly. Greater occlusal thickness of all crown materials resulted in higher crown fracture strength before chewing simulation. After chewing simulation occlusal thickness of lithium disilicate and PICN crowns had no significant influence on the fracture strength.
All crowns revealed fracture strength above the clinically expected loading forces. Therefore the durability of the tested CAD/CAM materials seems promising also in an occlusal thickness of 1.0mm.
本研究旨在评估由当前计算机辅助设计/计算机辅助制造（CAD/CAM）材料制成的牙冠的断裂强度。此外，还评估了牙冠厚度和咀嚼模拟对断裂强度的影响。
分别用二硅酸锂、氧化锆增强硅酸锂（ZLS陶瓷）和聚合物渗透陶瓷网络（PICN）制作牙冠，咬合厚度分别为1.0mm或1.5mm（n = 16）。将牙冠粘结在复合代型上。将每组8个样本的亚组在咀嚼模拟器中以5kg加载1,200,000次循环并进行热循环。最后，在万能试验机上对所有样本加载直至断裂。采用三因素方差分析来检测统计交互作用。在单因素方差分析和事后Tukey检验之后，用双因素方差分析测试材料之间的差异。
所有牙冠在咀嚼模拟中均未断裂。材料对抗断裂性有显著影响（p≤0.05）。在几乎所有组中，二硅酸锂的断裂强度值最高，其次是ZLS陶瓷。PICN的断裂强度值最低。咀嚼模拟显著提高了厚二硅酸锂牙冠的断裂强度。在咀嚼模拟之前，所有牙冠材料更大的咬合厚度导致更高的牙冠断裂强度。咀嚼模拟后，二硅酸锂和PICN牙冠的咬合厚度对断裂强度没有显著影响。
所有牙冠的断裂强度均高于临床预期的加载力。因此，所测试的CAD/CAM材料在1.0mm的咬合厚度下的耐久性似乎也很有前景。
