Stress magnitude and distribution in two-piece cement-retained zirconia implants under different loading conditions and with varying internal connection shapes

Zheng Xuying; Hu Hongcheng; Xu Libing; Han Jianmin; Di Ping

doi:10.12307/2026.599

Abstract：BACKGROUND:There is a risk of fracture in the clinical application of two-piece cement-retained zirconia implants,and different anti-rotation structures directly affect the reliability of the implant-abutment connection,and may indirectly affect the magnitude and distribution of stress conduction to bone tissue. OBJECTIVE:To explore the anti-rotation structure that is more suitable for two-piece cement-retained zirconia implant-abutment connection. METHODS:Six sets of implant system and surrounding bone models with different anti-rotation shapes(round triangle,three-petal shape,square shape,cross keyway shape,hexagonal shape,and Torx shape)were drawn in NX12.0 drawing software,and imported into ANSYS workbench2021 in X_T format,and the forces on simulated intraoral occlusion and implant placement were applied to them.By comparing the magnitude and distribution of stress on the implant,abutment,adhesive and surrounding bone,the fracture likelihood and the impact on the surrounding bone were predicted. RESULTS AND CONCLUSION:(1)Under vertical load,only the implant was affected by the shape of the anti-rotation structure.The implants with square and three-petal anti-rotation structures were subjected to the least force,but the placement direction of the three-petal anti-rotation structure affected the force results of the implant.Under oblique load,the abutment was subjected to the least force when the anti-rotation structure was a round triangle and three-petal shape,but the placement direction of these two shapes of anti-rotation structures would affect the force on the abutment;the implant was subjected to the least force when the anti-rotation structure was a cross keyway and hexagonal shape.Under torque load,the implant was subjected to the least force when the anti-rotation structure was hexagonal.Under the three loads,there was no significant difference in the magnitude and distribution of the force on the adhesive and surrounding bone under different anti-rotation structures.(2)The results showed that the anti-rotation structure was mainly related to the force on the implant-abutment connection part,and had little effect on the surrounding bone.For two-piece cement-retained zirconia implants,the hexagonal anti-rotation structure may be a mechanically advantageous implant-abutment connection type.