Functional Reconstruction Of Root Analogue Implants For Immediate Implantation

Immediate implantation has attracted more and more attention of clinicians because of its advantages such as short implantation cycle,less times of operation and high degree of aesthetics.At present,immediate implantation with traditional implants is still a step by step procedure for the preparation of the implant socket to adapt to the implant rather than the treatment process of the implant to adapt to the patient.In order to better meet the huge potential dental implant market in China,it is necessary to explore the implant with less surgical trauma,higher degree of osseointegration,comfort,beauty and function.According to the characteristics of oral CT images,the CT images were preprocessed firstly.Then Local Gaussian Distribution Fitting(LGDF)model is improved by adding the area term of the fused structural tensor,and the model constructed by using the structural tensor information has the effect of denoising.The segmentation effect of the improved model was obviously improved through the contrast test.Then the improved model was applied to segment the contour of the tooth crown,tooth neck and tooth root.In order to establish a root analogue implant with a higher degree of agreement with the alveolar socket of extraction,the obtained contour of a single tooth was converted from 2D CT coordinates to 3D point cloud format,and the obtained point cloud was fitted into a curved surface model of a single tooth using the Crust algorithm.The crowns and roots were separated according to the crown-root ratio.Then,the porous root implants with different porosity were designed by using the P structure and G structure of Triply Periodic Minimal Surface(TPMS)with specific pore size.To solve the problem of the mismatch between the titanium alloy implant and the surrounding bone tissue modulus,the designed TPMS structures with different porosity and pore structures were printed by 3D printing.The VIC-3D non-contact full-field strain system was used to measure the mechanical properties of the printed samples through compression tests.The equivalent modulus and equivalent Poisson’s ratio of each structure with different porosity were defined as the material configuration parameters to simulate Finite Element Analysis(FEA)of bone tissue around implant implantation.According to FEA results,root analogue implants with a porosity of 30%-40%contribute to the formation of long-term stable osseointegration.To prove the implantability of TPMS structure root analogue implants made by 3D printing.According to the cytotoxicity test,it was found that Ti-6A1-4V samples which had been directly treated in the air at high temperature had relatively strong cytotoxicity The cell proliferation experiment proved that cells could maintain good ability of division and proliferation no matter in which porosity and pore structure.The protein adsorption experiment found that the higher the porosity,the more protein adsorption amount,so the higher the porosity,the better the cho ice for the design of porous implant.According to FEA results,it is best to choose the root analogue implant with porosity of 40%.