Three Dimensional Finite Element Analysis Of Short Implants With Different Diameters By Bone Resorption At Implant Edge

Objective In maxillary molars with insufficient residual bone height,short implants are often used as the retainer of the superstructure.However,the diameter of short implants and the status of alveolar bone around the implants after implantation have certain effects on the stress of the implants and the surrounding bone tissue.In this study,short implant models of different diameters with or without marginal bone resorption were established in the maxillary molar region with insufficient residual bone height.Three-dimensional Dimension Finite Element Analysis was used.3-D FEA)method was used to compare the stress distribution of short implants with different diameters at the implant-bone interface with or without marginal bone absorption,in order to provide a theoretical basis for the clinical selection and application of short implants in the maxillary molar area where the residual bone height is not high enough.Methods The Cone Beam CT(CBCT)data of a patient with insufficient vertical bone height in the maxillary molar region were imported into Mimics software.The Mimics software was used to establish the maxillary molar region with or without marginal bone resorption.Using Solid Works software,short implants(7mm),repair abutment and implant superstructure models of different diameters(4mm,5mm and 6mm)were drawn respectively,and the above component models were assembled with the maxillary model,and then six complete models were constructed,namely three short implants of different diameters with or without marginal bone resorption models.Finally,ANSYS 2021 software was used to set the analysis parameter attributes,contact relations,mesh partitioning and loading conditions,and then the maximum displacement values of implants and the maximum Von Mises stress of implants and bone tissue around implants in the six models were compared.Results1.6 The position shift of implant models mainly concentrated on the neck of implant.The smaller the implant diameter,the larger the maximum implant displacement,regardless of whether the implant edge is accompanied by bone resorption.For short implants with the same diameter,the maximum displacement of implants in the marginal bone resorption model group was greater than that in the non-marginal bone resorption model group.2.The maximum Von Mises stress was concentrated at the second thread of the implant in the model with a diameter of 4mm and border bone absorption of 3mm,and the maximum Von Mises stress in the other models was concentrated at the connection between the neck of the implant and the abutment.3.In the no-bone absorption model group,the maximum Von Mises stress of cortical bone was distributed in the contact area between the neck of the implant and cortical bone.The maximum Von Mises stress of cortical bone was distributed in the contact area between the vertical absorption bone edge and the implant in the 3mm model group.4.The Von Mise stress peak value of the cancellous bone in the model with a diameter of6 mm and no bone absorption at the edge was concentrated at the contact between the penultimate thread at the root of the implant and the bone interface,and the Von Mises stress peak value of the other models was concentrated at the contact between the last thread of the implant and the bone interface.5.The maximum Von Mises stress of the implant and the surrounding bone decreased with the increase of the diameter of the short implant,regardless of whether there was bone resorption at the edge of the implant.When the diameter of short implants was the same,the maximum Von Mises stress of implant and surrounding bone in the group with marginal bone resorption model was greater than that in the group without marginal bone resorption model.Conclusion1.The stress at the implant-bone interface decreased with the increase of implant diameter,regardless of whether the implant edge was accompanied by bone resorption.The diameter of short implants is a key factor affecting the stress at the implant-bone interface.When using short implants to repair the maxillary molar area with insufficient vertical bone mass,implants with large diameter should be selected as far as possible under the condition that the bone width of alveolar bone allows.2.When the diameter of short implants was the same,the stress value of the implant-bone interface in the group with marginal bone resorption was greater than that in the group without marginal bone resorption.Therefore,bone resorption at the edge of implants is an important factor affecting the stability of short implants,and the occurrence and development of bone resorption at the edge of implants should be reduced or controlled as far as possible.