Numerical Analysis For Maxilla Micro-implant Anchorage System In Orthodontics

In recent years, micro-implant anchorage (MIA) system is widely applied in orthodontic treatment. The screw was inserted into jaw bone to resist the counterforce produced by orthodontic appliances. The micro-implant system is convenient to insert into bone, and it can take load as soon as embeded. It lead up to a revolutionary influence to the traditional orthodontic treat, and arose orthodontists's extensive attention.In this dissertation, on the basis of the research on the application of MIA and the clinic treatment, combine with CT scan technique and FEM software, a numeral MIA-teeth-maxilla three-dimensional model was established. The dynamics response process of bone was investigated after the mini-screw inserted. A numerical analysis was presented for stress and strain transformation process in maxilla when under the orthodontic loadings. It provide an important scientific criterion for the optimize of MIA. The main work and conclusions in this dissertation are as follows:â‘ Advancement what have been made in recent years about orthodontic biomechanics was reviewed in this dissertation. Finite element method in orthodontic numerical simulation was summarized. The application and investigation of MIA in orthodontical treatment were reviewed as the focus.â‘¡By CT scan technique,Mimics and ABAQUS, a new modeling method was presented. A reality MIA-tooth-maxilla three-dimensional model was established.The geometry comparability of model was improved in the extreme. And a new method to construct maxilla and teeth model quickly was explored.â‘¢Use elastic,viscous and plastic parts to construct a viscoelasto-plastic constitutive relation of bone. In the dissertation a three-dimensional finite element model which has the property of biomechanics was established describing the mini-screw and the bone. A numerical analysis was presented for the stress and strain transformation process of bone when the mini-screw under the orthodontic loadings. The analysis indicates under the orthodontic loadings, the elasto-plastic deformation with time effect occurs due to the viscoelasto-plasticity of bone. The stress level and plastic strain of bone can change with time in a certain extent. The stress decreased while plastic strain increased. A certain ratio of failure of micro-implant anchorage is inevitable in orthodontic treatment. The phenomenon is related to the stress distribution surrounding the micro-implant anchorage and the stress-strain distribution of the corresponding bone. In order to improve the clinic orthodontic technique,we should pay more attention on lots of factors,such as the geometry configuration of MIA, the biomechanics property of bone, and the contact mode of MIA with bone.â‘£Base on the simulation result which above-metioned, combine with clinic experiences, we can carry through the clinic treatment validate of MIA, and then select the optimize application project of MIA.