| Purpose As an implant of jaw,oral implants need good mechanical properties and biocompatibility.The titanium implants in common are dense structures similar to cylinders.On the one hand,when they were implanted in the rear molar area,traditional implants cannot achieve good initial stability because they do not conform to the shape of the sockets.On the other hand,the pure titanium structure of traditional implants are denser and the modulus of elasticity are much higher than jaw tissue.The stress shielding effect easily occurs when the occlusal force is loaded,resulting in absorption of the surrounding jaw and loosening of the implant.This study intends to use 3D printing techniques based on the morphological characteristics of rear molar area sockets to customize the immediate implants that can make up for the defects of traditional implants.Through finite element analysis experiments and some biocompatibility experiments in vitro to study the novel implant performance.Method(1)The CBCT image of the patient's teeth was separated and reconstructed to obtain a three-dimensional model consistent with the shape of the patient's extraction socket.Based on this three-dimensional model,the porous structure and abutment structure of the implant were designed,and three different porosity rates were set for the porous structure,namely 30%,50%,and 70%.(2)The vertical loading/Buccal side 15°loading/tongue side 15°in 120.66N on implant was analyzed by finite element analysis.Analyze the stress distribution of three kinds of porous implants with different porosity and the distribution of stress around the cancellous bone and compact bone under loading conditions.(3)Selecting pure titanium material using 3D printing technology to produce the implants,and performing surface etching and sandblasting.Three kinds of porous implants with different porosity were cells cultured in vitro with human osteoblast-like cells MG63.Three different porosity implants were compared by cytotoxicity assay,DNA content assay,alkaline phosphatase activity assay,and qRT-PCR assay to rate biocompatibility of implants in vitro.Results The biomechanical finite element model of the implant was successfully constructed.The analysis results showed that the three kinds of porosity implants were simulated under the conditions of simulated oral force(F = 120.66 N,vertical loading/Buccal side 15° loading/tongue side 15° loading).The stress distribution of implants is generally even.The value of the implant elastic modulus decreases with increasing porosity,and the elastic modulus of the 70%porosity implant is closest to the jaw tissue.At the same time,the stress value of cancellous bone decreases with the increase of implant porosity,and the stress of cancellous bone around the implant with 70%porosity is the lowest.In vitro biocompatibility tests showed that the implants were not cytotoxic.Human osteoblast-like cells MG63 showed good cell adhesion,proliferation and differentiation effects on all three kinds of porosity implants.The DNA content,alkaline phosphatase activity,and osteogenic differentiation-related genes(OCN,OPN,Runx2,Col-1)expression levels on the 70%porosity implants were significantly higher than those of the other two porosity implants(p<0.05).Conclusion The implant models with three kinds of porosity exhibited good mechanical properties.The higher the porosity of the implant,the smaller the stress of the surrounding cancellous bone,and the elastic modulus of the 70%porosity implant is closer to the human jaw tissue.In vitro biocompatibility tests showed that the etched sandblasted surface treated 3D printed pure titanium material was not cytotoxic.The MG63 human osteoblast-like cell implant can effectively adhere,proliferate and differentiate,and the 70%porosity implant is more favorable for the enrichment of MG63 cells,and has more excellent in vitro biocompatibility. |
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