A Preliminary Study On The Characteristic Of Interface Stress Distribution For TM Implant

Oral implant technology, which has a great advantage over other traditional partial denture methods in the aspects of function and aesthetic effect, has become one of the most important restoration methods for the missing or deficient teeth. At present, the implant systems applied in domestic markets are still relying heavily upon imports. The high cost, to a large extent, has limited the application range of the oral implant technology. Based on the above reasons, the independent research on the development of implant system with high quality and low-cost is of great significance to the related domestic scientific research institutions.The stress distribution on implant-bone interface has a close bearing on the functional state of the implant in future. If loading is proper, the stimulation to bony tissue is beneficial within the physiological range; on the other hand, when loading is enough large to exceed the physiological limits, local bone resorption, necrosis or bone micro-break would happen. The internal factors influencing the stress distribution on the implant-bone interface conclude material properties, shape and size design of the implant; while the external factors mainly consist of the anatomical configuration of bony tissue and the loading patterns. The development of design research on implant system are mainly focused on the material, shape, macro-structure, surface micro-structure of implant, the connection between implant and the upper structures, and so on.The applications of three-dimensional CAD modeling technology and finite element analysis technology are integrated in the piece of this paper to study and discuss the characteristic of interface stress distribution for TM implant, under both static loading and dynamic loading.3 implant models have been established, including the standard ITI model and the other two models of TM implant, in which TM-1 implant, whose diameter changes along half length of the implant (5mm) form a narrow width to standard diameter, has a bigger conical degree than TM-2 implant, whose diameter changes all the length of the implant (10mm).Establishment of finite element model for real implant-mandible systemObjectiveEstablish the finite element model of complete implant-mandible system, based on CT scanning technology and three-dimensional CAD modeling technology.Methods1. Obtain the geometric mandible model in DICOM format, based on the CT data scanning technology.2. Transform the two-dimensional picture-information to three-dimensional solid model to obtain the real solid mandible model, based on reverse engineering technology.3. Obtain the three-dimensional solid models of the standard ITI implant and TM implants, based on the CAD modeling technology.4. Obtain the three-dimensional geometric model of implant-mandible through assembling. 5. Transform the assembly model to finite element model by finely meshing in finite element software.Results1. Three-dimensional solid model of mandible has been established accurately and quickly, in great agreement with organizational form and structure.2. Standard ITI implant and TM implants have been constructed according to real entity. The shape of thread and taper are realistic.3. The implant-mandible assembly models have been finely meshed to ensure the reliability of the finite element simulations. Well meshing is a necessary foundation for the comparison of researches on the biology mechanics of different implants.Research on the interface stress distribution for TM implant under static loading,ObjectiveResearch on the characteristic of interface stress distribution for TM implant under static loadingMethods1. Experiment assumptions and boundary constrains.2. Make the finite element simulations for the three different implants under both vertical and oblique loading conditions.3. Get the related analytical targets; analyze the simulation results and draw the conclusions.Results1. The interface stress distribution under oblique loading is very different to that under vertical loading. Stress concentration is serious under oblique loading condition, which is bad for the well growth of the implant.2. Under vertical loading condition, for standard implant, the stress state of cortical bone is the worst, while the stress state of cancellous bone is the best; for TM-2 implant, the stress state of cancellous bone is the worst, while the stress state of cortical bone is better than that of standard implant; for TM-1 implant, the stress state of cortical bone is the most reasonable, while the stress state of cancellous bone is in the middle of the other two.3. Under oblique loading condition, the stress state of standard implant is the most reasonable; the stress state of cortical bone corresponding to TM-2 implant is the worst; the stress state of cancelllous bone corresponding to TM-1 implant is the worst, while that of cortical bone is rather reasonable (the maximum Von-Mises equivalent stress approximately equals that of the standard ITI implant).4. If one looks at the stress distribution from the first principle stress and the third principle stress, it can be found that TM-1 implant has a marked advantage over the standard ITI implant under vertical loading condition, while almost all of the mechanical targets of TM-2 implant are lower than the other two, thus not recommended.Simplified analysis on the interface stress distribution for TM implant under dynamic loadingObjectiveAnalyze the characteristic of interface stress distribution for TM implant under dynamic loadingMethods1. Establish the simplified implant-mandible assembly models2. Experiment assumptions and boundary constrains.3. Make the finite element simulations for the three different implants under oblique dynamic loading condition.4. Get the related analytical targets; analyze the simulation results and draw the conclusions.Results1. Successfully establish simplified implant-mandible models for finite element analysis. The simplified models can improve the efficiency of dynamic simulations.2. Based on various kinds of mechanical analytical targets including the Von-Mises equivalent stress, the first principle stress, the third principle stress and displacement, one conclusion can be drawn that the diameter changed TM implants have no advantage over the standard ITI implant under dynamic loading. The standard cylinder-shape implant is a more reasonable design.Conclusion1.Integrated CT scan data, reverse engineering, CAD modeling and three-dimensional finite element simulation of the technical computing line in biomechanics simulation research, especially in dental technology in the cultivation of outstanding superiority, playing an irreplaceable role significant.2.The compact bone and cancellous bone showed a significant stress concentration in critical condition, static loading and dynamic loading of the results show, the standard implant showed a more excellent mechanical performance under oblique loading.3.The compact bone and cancellous bone stress distribution more uniform, compared, TM-1 implants showed good mechanical characteristics, clinical application could be considered under vertical loading4.TM implant as a new implant, need to consider many aspects, and comprehensive involving implant material properties, taper, thread, radius, length, etc. of various factors, will gradually be improved.