Multi-rooted Implant Design And Manufacture Based On SLM Technology And Animal Experiment Study

As dental implant is beneficial for aesthetical effect and can restore the edentulous region’s function without damaging the adjacent teeth,it has become a preferred choice for edentulous repair.Human molar crowns are relative huge,and in most time,they are multi-rooted.When people chewing food,molars will bear largest vertical occlusal force against with relative big lateral load at the same time.The rigid connection between implant and bone tissue is achieved by osseointegration.This way can well oppose pressure stress but will become fragile if bearing tensile stress and shearing stress.While the most implants today are single-rooted with revolution structure which have drawback on against lateral force.In terms of the structure of anatomy,human jaw can be divided into cortical and cancellous bone from outside to inside.The two structures have different mechanical properties,but the existing implants have the same mechanical properties that are much higher than bone tissue.This is why the existence of stress shielding have influence on the implant’s success rate in the long term.Besides,the surface preparation methods of existing implants are just for increasing surface roughness or fine structure of which have no change on the combination mode between bone and implant,this method can’t form the intertwined mechanical self-locking structure.The purpose of this study is to design a kind of multi-rooted implant(MRI)that can meet the mechanical requirements of the molars region.In order to match the bone property,pore structures with different size and porous were designed on the surface of MRI.The Selective Laser Melting(SLM)technology was used to manufacture MRI.The osseointegration between MRI-bone interfaces was evaluated by animal experiment.And the biomechanical combination of implant-bone was assessed by pushing out and torquing test.The main work and research results are as followed:1.Presenting a multi-rooted implant system by considering the anatomical characteristics of the molar teeth and human jaws,a series of parameters about implants with porous structure on the surface were established.2.Establish the biomechanical model of implant system including the structure of implant,abutment,cortical bone and cancellous bone,acquiring the stress distribution of implant/bone tissue by the finite element method.The result showed that,comparing with single-rooted implant,the multi-rooted implant can significantly decrease the stress concentration.MRI with porous structure could promote the strain level of bone tissue upon bone modeling threshold.3.The craft to fabricate multi-rooted implant with porous structure was presented.The shapes of pore structure were observed by Micro-CT scanning and scanning electron microscopy(SEM).The result showed that the novel implant could satisfy the design requirement.4.The osseointegration and biomechanical property of MRI was investigated by animal experiment.The result of micro CT result and hard tissue slices show that the multi-rooted implant with porous surface structure have good bone conduction ability which is beneficial for the growth of bone tissue.The pushing out and torquing test show that the muti-rooted implant have good ability to resist shear and torsion.