Numerical Simulation And Analysis Of The Biomechanical Character Of Implant-supported Fixed Dentures

The biomechanics of implant-supported fixed dentures is an important factor for improving the mission success rate.And improving the success rates of implant-supported fixed dentures is an urgent problem in prosthodontics clinical practice.So it becomes a research focus at home and abroad.At present,it is effective to investigate biomechanics of implant-supported fixed dentures using finite element method.In this way,the disadvantages of experiments can be conquered.Finite element method could simulate oral cavity circumstance factually and process mechanical analysis for different materials by one finite element model.So,it is significant in meliorating the biomechanics and improving the success rates of implant-supported fixed dentures.The CAD models of fixed bridge,implants,cortical bone and cancellous bone were founded based on 3D reverse engineering technology at first.The model could reflect the actual configuration of oral tissue.Combine with the theoretical basis of finite element method and fundamental equations,the CAD models were meshed,the material attribute were defined and the boundary conditions were enacted.And the 3D finite element models were founded.On the basis of these models,the connector sectional areas of fixed bridges were changed for analyzing the stress distribution and displacement of the implant-support denture and surrounding osseous tissue.The results showed that the aclinic forces bring greater stress concentration and displacement compare with vertical forces.It was proved that increasing the connector sectional areas to some extent can decrease load in implants and fixed bridges themselves effectively.But too large connector sectional areas would induce negative effect on the surrounding tissues.Therefore,the bridge with large connector sectional areas should be used to protect the fixed bridge connector.But the actual situation of patients should also be considered.When the patients' bone is loose,the bridge with too large connector sectional areas should not be used for implanted-supported fixed dentures prosthodontic.The pattern and pitch of the screw thread on implants and osseous tissues were founded to study the influence of different screw threads on implant-supported fixed dentures and surrounding osseous tissues.The results indicate that the stresses were greater when the pitches were too small or too big and 0.8mm and lmm are the fitting pitch.The V-shaped screw thread with 60°screw- thread angle and 0.8mm pitch,the V-shaped screw thread with 90°screw- thread angle and lmm pitch,buttress screw thread with 30°screw- thread angle and reverse buttress screw thread with 45°screw-thread were proved having better performance.The study provides theoretical basis for the biomechanics of implant-supported fixed dentures.It has certain guiding significance for clinic oral medicine.