| ObjectiveIn recent years,taper-integrated platform-switching implant has become more and more popular in clinical practice.This experiment studied the influence of different connection designs of the implant on the stress of the abutments and abutment screws.MethodsWith Astra 5.0S TX 5 mm*11 mm implant system as reference,we established implant models(Platform-switching:0.2 mm,0.4 mm,0.6 mm,0.8 mm,1.0 mm,called PS0.2/PS0.4/PS0.6/PS0.8/PS1.0;Taper:6°,8°,10°,called T6/T8/T10)using modeling software UG.The models were then loaded 600 N vertically?225 N vertically?225 N obliquely(45°)and 225 N horizontally(called F1/F2/F2/F4)from the crown using Ansys workbench finite element analysis software and finally we got 60 models.For example,the model that had 0.2 mm platform switching and 6° taper and received 600 N vertical load was named PS0.2T6F1.Von-mises stress and equivalent elastic strain of the abutments and abutment screws were analyzed.Results1 Effects of different amount of platform switching on the von-Mises stress and equivalent elastic strain of the abutment and abutment screws(1)With the increase of the platform-switching amount,the peak von-Mises stress and the peak equivalent elastic strain of abutment and abutment screw increased.In addition,the variation amplitude:horizontal loading>oblique loading>vertical loading.(2)The peak von-Mises stress>690 MPa in models PS1.OT8F3 and PS1.0T10F3 under 225 N oblique load.When 225 N was applied horizontally,the peak von-Mises stress of the models with a platform-switching amount of 0.8mm or more was greater than 690 MPa.2 Effects of different abutment taper on the von-Mises stress and equivalent elastic strain of the abutment and abutment screws(1)Changing of the abutment taper had no significant effect on the peak von-Mises stress and peak equivalent elastic strain of abutments under 600 N and 225 N vertical loads;Peak von-Mises stress and peak equivalent elastic strain of abutments increased as the abutment taper increased under 225 N oblique and 225 N horizontal loads except for models with the platform switching amount of 0.6mm.(2)Peak von-Mises stress and peak equivalent elastic strain of abutment screw increased as the abutment taper increased except for models with the platform switching amount of 0.8 mm under F1,models with the platform switching amount of 0.4 mm under F2 and models with the platform switching amount of 0.2 mm under F3.3 The influence of the platform switching amount on the von-Mises stress and equivalent elastic strain of the abutment and abutment screws was greater than the abutment taper.4 The maximum stress of the abutment was concentrated at the neck(platform level of the implant)of the abutment in 81.67%models.The stress of the abutment screw was concentrated under the screw head in all models.Conclusions(1)The increase of the amount of platform switching made the abutment and the abutment screws bear more force in the occlusion process.So in order to reduce the occurrence of mechanical complications after implantation and restoration,this study suggested that the implant system with the minimum amount of platform transfer should be selected within a certain range.(2)When the amount of platform-switching was greater than 0.8 mm,the max,imum stress on the abutments and screws exceeded the yield strength of pure titanium,which is 690 MPa,suggesting that this design should not be used in clinical practice.(3)Although for some models with specific platform transfer amount,the peak von-Mises stress and peak equivalent elastic strain of abutment and abutment screws increased with the increase of abutment taper,on the whole,changing the abutment taper had no significant effect on reducing mechanical complications after implantation and repair.(4)The neck of the abutment and the underside of the abutment screw head were the weak points in the implant system.The design of these parts can be optimized in future implant research and development. |
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