The Stress Analysis Of Platform Switching

Objective It was observed that bone resorption was occurred around the neck of implant in some cases interferencing the success effect of implant. However less bone resorption was possible when using platform switching. There were many reasons for bone resorption. Biomechanical advantage was a important reason. The purpose of this study was to simulate a 3D finite element model of implant-supported maxillary central incisor using platform switching abutment and to observe biomechanical advantages of the platform switching.Method Using the Solidworks 2007 and ANSYS workbench11.0 software, the three-dimensional finite element models were simulated platform switching abutment connection with implant-bone complex. And the CAD models were put into the ANSYS workbench analysis software to assemble implant-bone complex according to different parts of the experiment. Vertical and horizontal loading were applied to the models. Then stress distribution and maximum stresses in and around implant area when with different abutment materials and in different bone quality conditions were analyzed.Result (1)The three-dimensional finite element models of platform switching abutment connection with implant-bone complex were simulated successfully.(2)The stress distribution with ceramic abutments were similar to titanium abutment. The three kinds of abutments stress distribution were concentrated in the connection with implant at the labial side. The implant stress distribution was concentrated at the neck of implant. The cortical bone stress distribution was concentrated in the area of the connection with implant at the neck. The cancellous bone stress distribution was concentrated in the area of the connection with the cortical bone. The crown stress distribution was concentrated in the area of the loading part. The maximal Von mises stress of titanium abutment support was higher than ceramic abutment support under vertical loading in the area of the neck of the cortical bone and implant. Both were model C>model B>model A. But in the area of abutments, they were just the opposite. They were model A>model B>model C. The maximal Von mises stress in the area of crown and cancellous bone had no significant difference between three models.(3)Four models had similar stress distribution. The cortical bone stress distribution was concentrated in the area with connection of implant at the neck. The four kinds of abutments stress distribution were concentrated in the connection with implant at the labial side. The crown stress distribution was concentrated in the area of the loading part. In the distribution of the cancellous bone area, Class 3 bone quality and Class 4 bone quality were more concentrated while Class 2 bone quality was spread to the mesial and the distal side. The maximal Von mises stress in the area of cortical bone and abutment were both modelⅣ>modelⅢ>modelⅡ>modelⅠ.In the area of crown was just the opposite. The maximal Von mises stress in the area of implant were modelⅣ>modelⅢ>modelⅠ>modelⅡ. The maximal Von mises stress in the area of cancellous bone were modelⅢ>modelⅣ>modelⅡ. (4)The stress distributions were similar when applied different directions of loading. Comparing the vertical loading, the maximal Von mises stress in and around the implant were higher when applied horizontal loading, especially in the area of abutment and implant.Conclusion (1)The stress distribution of the implant–supported maxillary central incisor using platform switching abutment with ceramic abutment was similar to titanium abutment. It didn't have more stress in the implant and the cortical bone when using abutment with high hardness materials. Abutment material didn't affect the stress distribution in the crown. It should be careful of fracture because it may cause the stress concentrated when the abutment using high hardness material.(2)The stress distribution in different bone quality conditions were similar. In ClassⅡand ClassⅢbone quality condition, the maximum Von Mises stress in and around implant were more appropriate than the other two conditions.(3)It should be reduced the horizontal loading which may cause high stress concentration leading to bone resorption or leading to crown and implant fracture.