比较4种CAD/CAM氧化锆抗压强度和断裂模式

Comparison of compressive strength and fracture mode between four kinds of CAD/CAM zirconia

目的通过赫兹触压实验分析比较4种牙科CAD/CAM系统氧化锆材料的抗压强度和断裂模式。方法制作Cercon smart、Lava、Porcera、CEREC 3共4种CAD/CAM系统氧化锆平板试件各6个。通过赫兹触压实验及数字图像相关法,对各组试件的临界载荷值、破坏载荷值及断裂模式进行分析。结果平板试件均在饰瓷内部以中位裂纹的形式起裂,以弧形方式传递至核瓷表面,沿饰瓷和核瓷界面分层;4种系统之间临界载荷值差异不具有统计学意义(P>0.05),破坏载荷值差异具有统计学意义(P<0.05),其中CEREC 3系统最高。结论 4种CAD/CAM系统氧化锆材料抗压强度能基本满足临床运用中口内最大咬合力的需要;其破坏模式相似,出现微裂纹及完全断裂仅发生于饰瓷,饰瓷强度仍需加强。

Objective To analyze the compressive strength and fracture mode between four kinds of dental zirconia CAD/CAM ceramic materials by Hertzian contact test.Methods Four CAD/CAM ceramic materials including Cercon smart,Lava,Porcera,and CEREC 3 were selected.Six zirconia sectioned flat specimens were prepared in each group.The critical load and fracture load as well as the fracture mode for each specimen were analyzed with digital image correlation（DIC） technique.Results It was found that cracks were initiated at the middle level of the veneer below the contact zone and propagating along an arc curve into the core/veneer interface,which eventually caused the debonding of the core/veneer layers.For the four ceramic systems,there were no significant differences in the critical load（P0.05）,while there were significant differences in the fracture load（P0.05）.Conclusions The compressive strength of the four zirconia CAD/CAM ceramic materials could substantially meet the clinic requirement for oral functions regarding the maximum occlusal load.Crack initiation and complete fracture only occurred in the veneer,which indicated that the strength of the veneer should be further reinforced.