Three Dimensional Finite Element Analysis Of The Stress Distribution Of Bone Tissue Around Porous Titanium Implant

Background:Due to the elastic modulus of titanium implant is much higher than that of the surrounding bone tissue,it is easy to produce stress shielding effect.In order to reduce the bone absorption and bone atrophy caused by stress shielding,many scholars have constructed porous titanium implant.The researches show that the porous structure provides more space and surface area for bone cell adhesion and bone growth,and can improve the osseointegration rate and has good biocompatibility.In addition to the excellent biocompatibility of the implant,the key to the success of the implant should be good biomechanical properties,while the three-dimensional finite element analysis is an effective method to study the biomechanical properties of the implant.Purposes:To analyze the stress distribution of different types of bone tissue around porous titanium implant in different mechanical loads,to further evaluate the biomechanical properties of porous titanium implant,so to make a comprehensive analysis of porous titanium implants and evaluate the application value of it in dental implants.Methods:1.Maxillary first premolar crown,abutment and implant model in bone quality(D3 type)were constructed.Implants divide into five groups:solid group,central pillar 1.5mm and outer porosity 30%,central pillar 1.5mm and outer porosity 40%,central pillar3.1mm and outer porosity 30%,central pillar 3.1mm and outer porosity 40%.Different loads(150N vertical force,50N lateral force,simulation ultimate force)were applied to the occlusal surface of implant and maximal equivalent von-Mises stress was evaluated.2.A couple of simplified maxillary segment models vary in bone quality(D1,D2,D3 and D4 type)were constructed.To evaluate the stress distribution of different types of bone by simulating the ultimate load.Results:1.The stress distribution patterns of solid implants and porous structures were similar for different types of bone tissue.The vertical loading stress concentration area is mainly located in the neck of implant bone,annular distribution,stress concentration in the buccal cortical bone for lateral force.2.Compared with the vertical loading,the stress concentration range of the bone tissues increases under lateral loading.With the increase of porosity,peri implant bone stress concentration area with the decrease,when the porosity is 40%,the reduction is more obvious.3.Different mechanical loading,the stress value of bone tissue around porous implant is greater than the solid structure,the maximum stress value were located in the neck of implant cortical bone,and with the increasing of the applied mechanical load,the maximum stress value increases.The maximum stress at the bone interface around the implant under lateral loading is much higher than that under vertical loading.4.With the increase of porosity of the porous implant,the maximum stress value of the bone increased,the same porosity of the porous layer,when the porous layer is thicker,th stress value of the bone is greater.5.The maximum stress value of the surrounding bone tissue changed with the change of bone,and there was no significant relationship with the implant structure.D4 type bone>D3 type bone>D2 type bone>D1 type bone?Conclusion:1.Different mechanical loading,the maximum stress of bone around porous titanium implant is greater than the solid implant,and with the increase of pore structure,peri.implant bone stress increases.No matter what kind of structure,the maximum stress value of the bone around implant changes with the change of bone,the lower the bone density,the greater the maximum stress value of the bone tissue around the implant.When the implant is subjected to lateral force,the stress of the bone tissue around the implant is greater than the vertical force.2.When the bone is more dense and the bite force is smaller,the porous implant is more advantageous to the bone tissue and the stress of the bone tissue around the implant,so as to counteract the stress shielding.3.The lower the bone density,the greater the bite force,the more careful use of the porous implant,strictly control the lateral force and excessive bite force,in order to prevent the occurrence of pathological load.