Biomechanical Characteristics Of Micro-Implant Orthodontic Anchorage System: A Three-Dimensional Finite Element Analysis

ObjectiveAnchorage design and control is one of the most important factors in a successful orthodontic treatment. Single tooth, a group of teeth or extraoral anchorage can be used in anchorage control. Traditional anchorage methods have many problems such as the stability, comfort and convenience to the patients, and it has such limitations that it requires excellent patient cooperation.With the use of dental implants, miniplates and screws as anchorage, the orthodontic teeth movement without anchorage loss has become possible. Among these devices, the microscrew implants have the advantages of easy placement and removal, with minimal anatomical limitations because of their small size; immediately loadable; well tolerated by patients and inexpensive. A large a-mount of clinical and laboratory researches have demonstrated that the micro -implant anchorage method could safely be loaded with 2 ~3N orthodontic force and remain stable in the loading period, and it was useful for achieving an excellent improvement of the dental deep bite and gummy smile in the patients that was very difficult to cure by traditional anchorage method.The three -dimensional finite element method (3D -FEM) is a computer - aided mathematical technique for obtaining approximate numerical solutions to the abstract equations of calculus that predict the response of physical systems subjected to external influences. FEM allows stress distributions and levels to be evaluated in systems with irregular geometry and nonhomogeneous physical prop-erties. The technique has been applied, with some success, in orthodontic research.Finite element method (FEM) is the most reliable method for providing a clear understanding of the occurrences in an unknown process. This method is by far the best one to provide the researcher with simulations as real as possible. One of the most important advantages of this method, which cannot be found in any in vitro experiment, is that it provides the ability to optimize a process numerically and accurately. Application of a new anchorage design without considering its complete functions is not in accordance with medical ethics. In addition, it is not possible to evaluate the treatment effects of a new anchorage design in the mouth so accurately. Therefore, FEM was selected to accomplish the calculation of displacements.The purpose of this study is to establish a three - dimensional finite element model for orthodontic anchorage micro - implant. And to analyze the influence of different titled angle on the biomechanical characteristics of orthodontic anchorage implant - bone interface.MethodsUse ANSYS ( Analysis System) finite element analysis software to perform the finite element modeling of the micro - implant with 7 different tilted angle, including30 ,40°,50°,60°,70°, 80° and 90°. A simulated orthodontic force , which was 200 grams , loaded mesiodistally to the mathematical models, analysis of the stress and displacement distribution on the implant - bone interface.ResultsThe distribution of the stress and displacement could easily be obtained from the micro - implant 3D - FEM models. The Von - Mises stress were focuses mainly on the cervix of the implant - bone interface, and it decreased rapidly in the cortical bone , so the Von - Mises stress in the spongiosa bone is very small. As the titled angle increased , the maximum Von - Mises stress at the...