Three-Dimensional Finite Element Analysis Of Different Six-Implants Position And Different Implants Supporting Fixed Prosthesis In Edentulous Mandibular

ObjectiveTo establish a three-dimensional finite element model of edentulous mandible,implants of Ankylos,mandibular full-arch and segmental-arch prosthesis,and to analyze the stress distribution of different sites in the full-arch fixed prosthesis design of edentulous jaw supported by six implants.To analyze the stress distribution of different sites in the two-segmental-arch and three-segmental-arch fixed prosthesis design of edentulous jaw supported by six implants.And to compare the stress distribution around implants among full-arch and segmental-arch prosthesis design of edentulous jaws.To evaluate and clarify the clinical effects of different designs supported by six implants from the perspective of biomechanics.MethodsObtaining the three-dimensional data of the upper and lower jaws of adult normal jaws by CT scanning.Separating the mandibular and mandibular dentition models Mimics software on the computer.Detaching the mandibular continuous crown and edentulous mandible model by Boolean calculation in 3-matic software.Performing the precise surface treatment of edentulous jaw model and mandibular continuous crown in GeomagicStudio software.Establishing the 3D solid model of edentulous mandible and full-toothed prosthesis completely.Drawing the implant and abutment model in Solidworks software.These part-models were assembled into different models according to different implant sites designs in mandible and different fixed prosthesis designs.Establishing three-dimensional finite element models of different six-implants sites and different implants supporting fixed prosthesis in edentulous mandible.In the ABAQUS finite element analysis software,each model was loaded on two types of occlusal force.The one is from the occlusal force of posterior teeth and the other force is from the occlusal force of anterior teeth.Analyzing the stress distribution of the bone around the implant.Analyzing the effects of the stress distribution of the supporting tissues of different six-implants sites designs and different implants supporting fixed prosthesis in mandibular by using the ABAQUS software.Results1.Established a model of edentulous mandible,implant of Ankylos,full-arch fixed prosthesis,two-segmental-arch fixed prosthesis and three-segmental-arch fixed prosthesis.2.9 different planting sites designs were devised in total based on the fixed prosthesis of six implants in edentulous mandible without cantilever structure,based on the prosthesis are designed to be repaired to the second molars.At the same time,the common implant sites are symmetric and evenly distributed.There are 15 models named Model-A to Model-O of the different planting sites disigns were combined with the full-toothed prosthesis and segmentle-arch prosthesis.3.There are 9 different sites designs in the edentulous mandible with full-arch fixed prosthesis supported by 6 implants.Each model was loaded with posterior occlusal force and anterior occlusal force respectively.Resulted a stress concentration phenomenon.The comparison of these 9 models shows that the sites designs of 7,5,1,and 7,4,2,and 7,4,1has a better the stress distribution,which are smaller of their stress peak data.4.There were 3 different six-implants sites disigns with two-segmental-arch fixed prosthesis in edentulous mandible.Loading the posterior occlusal force and anterior occlusal force to these three models,the comparison showed that the the sites designs of 7.5,1 and 7,4,1 has a better the stress distribution,which are smaller of their stress peak data.5.There were also 3 different six-implants sites disigns with three-segmentalarch fixed prosthesis in edentulous mandible.Loading the posterior occlusal force and anterior occlusal force to these three models.These three designs has a large value of stress distribution around the implant,which is unfavorable for the preservation of the jaw bone,and there may be a risk of resorption of the bone.6.Loading the occlusal force of the posterior teeth and anterior teeth,the bone stress around the implant of the full-arch fixed prosthesis designs is lower than the design of segmentel-arch prosthesis.Conclusions1.The analysis results of all the models in this experiment showed that the cortical bone around the top of the implant and the top of the implant were stress concentration areas.2.In the case of the same site of six-implants in edentulous,the stress distribution of the implant top of full-arch designs is more dispersing and smaller than two-segmental design.The full-arch type is apt to reduce the incidence of alveolar bone resorption and ensuring a long-term retention of the implant.3.In the case of six-implants supporting fixed prosthesis reparing fourteen crowns and without cantilever structure in edentulous,compared with the design of the full-arch prosthesis and the two-segmental-arch prosthesis,it is not recommended to design a three-segmental-arch prosthesis.There is a large concentration of stress in the top of the implant,which may have a greater risk of bone resorption.4.The better designs of six-implant supporting full-arch fixed prosthesis in edentulous is 7,5,1 or 7,4,2 or 7,4,1;The better designs of six-implant supporting two-segmental-arch fixed prosthesis in edentulous is7,5,1 or 7,4,1.Therefore,the planting sites of 7,5,1 and 7,4,1 are more flexible,which can be designed for full-arch fixation and can also be designed for two-segmental-arch fixed prosthesis.