两种不同厚度椅旁CAD/CAM全瓷材料断裂强度的实验研究

The effect of differential thickness on the fracture load of CAD / CAM enamic blocs

目的：研究不同厚度对于椅旁计算机辅助设计与制作（computer aided design/compnter aided manufacturing,CAD/CAM）全瓷材料断裂强度的影响。方法 ：制备50颗离体牙试件,随机分为5组,分别与厚度为1.0、1.5、2.0、2.5、3.0 mm的椅旁CAD/CAM全瓷材料——Vita enamic瓷块和Vitablocs MarkⅡ瓷块,用panavia f树脂粘结剂粘固。粘固1 h后水浴24 h,测试其静态断裂强度值,并观察其断口形貌。结果：随着厚度增加,Vita enamic瓷块和Vitablocs MarkⅡ瓷块试件的断裂强度也逐步增加。在1.0-2.0 mm厚度组,Vita enamic瓷块和Vitablocs MarkⅡ瓷块试件的断裂强度值相近;在2.5-3.0 mm厚度组,Vita enamic瓷块的断裂载荷值较Vitablocs MarkⅡ瓷块显著增加。结论 ：Vita enamic瓷块具有与Vitablocs MarkⅡ瓷块相似的断裂强度。在厚度大于2.5 mm时,Vita enamic瓷块表现出更为优越的机械学强度。

Objective： To investigate the effect of computer aided design / compnter aided manufacturing（CAD / CAM） enamic blocs with different thickness on the fracture load. Methods： Fifty test specimens were fabricated with isolated tooth in the study. These specimens were divided randomly into two groups：the experimental group（Vita enamic）and the control group（Vitablocs MarkⅡ）. In each group,these specimens were divided randomly into five differential thickness sub groups（1.0 mm,1.5 mm,2.0 mm,2.5 mm and3.0 mm）. Every specimen was cemented on the differential thickness bloc with panavia f resin adhesive system. They were stored in distilled water at 37℃ for 24 hours prior to fracture testing. Then, the fracture load was tested in a universal testing machine.Results： Accompany with the increase of thickness of bloc,the increase of fracture load was detected in both groups. When the bloc thickness lied from 1 mm to 2 mm,the fracture load in both groups was similar. But from 2.5 to 3 mm,the fracture load of Vita Enamic was higher than that of Vitablocs MarkⅡ. Conclusion： The fracture load between the Vita enamic and Vitablocs MarkⅡ was similar. Only when the thickness is over 2.5 mm,the mechanical property of Vita enamic was super to that of Vitablocs MarkⅡ.