| bjective:using the Pro/Engineer.wildfire4.0, MSC.Patran2010software to establish the three-dimensional finite element model of spongy bone,cortical bone and the implant of the molar area. By the means of three-dimensional finite element method analysising of peri-implant bone tissue Von Mises equivalent stress distribution and stress concentrated area when the length of6mm,8mm,10mm implants were tilted0°,15°,22.5°,30°implanted in the molar region under the vertical load and exploring the implant angle and length how to affect the stress distribution of the surrounding bone tissue, providing some mechanical theoretical basis for clinical implant restoration design. Methods:1.With Pro/E4.0software, establishment solid model of the cortical bone, the cancellous bone and a solid model of cylindrical threaded implant and abutment which diameter of4.6mm, length of6mm,8mm,10mm and height of4.5mm respectively.Then assemble and install the implant that the length of6mm,8mm,10mm to0°(vertical) and vertical basis tilted to nearly15°,22.5°,30°to the jaw bone of cancellous bone and cortical bone.base stations with matching angle are assembled to the implant for correcting the implantation angle.12solid model are assembled, save12conditions to sat format respectively.2.Import sat. File into MSC.patran2010to mesh with a10-node tetrahedral form, change the system default parameters and local refinement, save to iges format.3.Import iges. file into MSC.Marc.Mentat. -2010R3opengl, set material parameters of implants, cancellous bone and cortical bone as well as the contact relations of adjacent interface and friction coefficient;fix constraint in the jaw bone of eight corners,imitate the constraint of mandible;the200N vertical loading force are forced in the center of the implant abutments.Comparative analysis of Von Mises equivalent stress distribution and the changes of stress concentration zone at the peri-implant bone tissues when different angles and lengths of implants are implanted in the molar region, make a chart, draw a line chart. Results:1.Establish a three dimensional finite element model of jaw bone and implant with biomechanical properties.2.When the length of6mm,8mm,10mm implant were tilted0°implanted, the stress concentration of peri-implant bone under the vertical loading force was all distributed in the implant neck cortical bone and in a form of ring, the root apex of the cancellous bone as the second,stress of the rest cancellous bone is smaller and distributed uniformly. The peri-implant bone stress gradually decreases with the increase of the length. When the length of6mm,8mm,10mm implant were tilted0°implanted, the maximum Von Mises equivalent stress around peri-implant bone was25.7055MPa,22.1808MPa,16.2553MPa respectively. When the length of8mm,10mm implant was compared with6mm implant, the peri-implant bone tissue such as the maximum Von Mises stress was reduced by10.61%,36.41%.3.When the length of6mm,8mm,10mm implant were tilted implanted,the stress concentration of peri-implant bone under the vertical loading force was all distributed in the implant neck cortical bone, stress distribution of the mesial surface is more focused than the distal surface, the buccal and lingual surface.As the angle of different length implants increase, which the bone interface stress rises. When the length of6mm implant which were tilted nearly15°,22.5°,30°than0°implanted were compared, the maximum Von Mises equivalent stress of the peri-implant bone increased by27.95%,94.65%,174.51%respectively; When the length of8mm implant which were tilted nearly15°,22.5°,30°than0°implanted were compared, the maximum Von Mises equivalent stress of the peri-implant bone increased by5.56%,75.38%,184.41%respectively; When the length of10mm implant which were tilted nearly15°,22.5°,30°than0°implanted were compared, the maximum Von Mises equivalent stress of the peri-implant bone increased by13.36%,57.11%,246.02%respectively; when length of8mm,10mm implant than6mm implant was tilted15°implanted, the maximum Von Mises stress of the peri-implant bone is reduced by26.26%,43.66%respectively; when length of8mm,10mm implant than6mm implant was tilted25°implanted, the maximum Von Mises stress of the peri-implant bone is reduced by19.46%,48.67%respectively; when length of8mm,10mm implant than6mm implant was tilted30°implanted, the maximum Von Mises stress of the peri-implant bone is reduced by7.38%,19.84%respectively. When the length of6mm implant was tilted0°implanted,8mm implant implantation was tilted15°implanted and10mm implants was tilted22.5°implanted, the maximun Von Mises stress of the peri-implant bone was25.7055MPa, 24.2536MPa,25.6831MPa respectively. Conclusion:1.using the Pro/Engineer.-wildfire4.0, MSC.Patran2010, MSC.Marc.Mentat.2010R3opengl software to establish the three-dimensional finite element model of implant and peri-implant bone that high speed, accuracy and strong flexibility.2.The length of the implant influence of stress and stress distribution of implant-bone interface.When the implant was tilted0°implanted, The maximum Von Mises equivalent stress of the peri-implant bone gradually decreases with the increase of the length under the vertical load, the stress distribution tends to be uniform.3.When the same length of implant was implanted, the maximum stress of the peri-implant bone increase with the tilt angle increasing.4. When the implant with the same tilt angle wast implanted, the maximum stress of the peri-implant bone reduce with the implant length increasing.5.Tilt Implant can increase the effective length of the implant, but when the correspoding length of the implant vertical implantation than tilt implantation is more conducive to the stress distribution of the peri-implant bone. |
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