粘接剂吸水老化对CAD/CAM二硅酸锂单层瓷冠触压承载能力的影响

Effects of adhesives aging in water on load bearing capacity of monolithic CAD/CAM lithium disilicate crowns

目的利用实验和数值模拟方法对CAD/CAM二硅酸锂单层冠的触压破坏进行分析,研究粘接剂吸水老化对瓷冠承载能力的影响。方法设计并制作二硅酸锂单层冠切片试件,平均分组保存于空气和水环境中30 d后进行触压实验,对比分析其承载力;通过电子扫描显微镜对切片试件的断裂面和粘接界面进行观察;利用数值模拟方法计算瓷冠的应力分布,分析单层冠承载能力受粘接剂老化的影响。结果保存于空气中的单层切片全瓷冠承载力为(561.51±65.66)N,粘接剂吸水老化后单层冠承载力为(398.09±90.20)N,有显著性差异;粘接剂老化后粘接强度降低,导致瓷层下表面处拉应力增大,使得单层冠更易产生破坏。结论粘接剂遇水老化使界面的粘接力下降,改变了单层冠承载时的应力分布,降低了单层冠的承载能力。研究结果为临床中CAD/CAM单层冠修复系统的设计和制备提供参考依据。

Objective To analyze the contact failure of monolithic lithium disilicate CAD/CAM crowns by experi- ment and numerical simulation, and explore the influences of adhesives aging in water on load-bearing capacity of the crowns. Methods The specimens of sectioned monolithic lithium disilicate crowns were designed and manu- factured, and evenly divided into two groups and stored in the air and in the distilled water for 30 days, respectively. The specimens were then subjected to monotonic contact loads to compare and analyze their load-bearing ca- pacity. The fractured surfaces and adhesive interfaces of the specimens were observed by scanning electronic microscope. Meanwhile, the stress distribution on the crowns was calculated by numerical simulation to analyze the adhesives aging influence on load-bearing capacity of the crowns. Results The fracture loads on crowns stored in the air and in the water were （561.51 ± 65.66） N and （398.09 ± 90.20） N, respectively, indicating a significant difference. The tensile stress increased considerably at lower surface of the ceramic crown due to the reduction of adhesive strength at the interface of ceramic crown and substrate, which could increase the propensity of contact failure. Conclusions The adhesives aging in water reduces the bonding strength, and accordingly changes the tensile stress distributions, which can lower the load-bearing capacity of the lithium disilicate crowns. The research finding provides references for the design and manufacturing of all-ceramic CAD/CAM restored crowns in clinic.