Measurement Of Orthodontic Force And Biomechanical Simulation Of Teeth In The Process Of Orthodontic Treatment

Fixed orthodonic technique is the most effiective orthodonic treatment,in which the shape of formed orthodonic archwire is the determinant of orthodonic force.At present,in the process of orthodonic treatment,most orthodonic physicians rely on experience and feedback of treatment to determin the shape of archwire.There is a lack of quantitative standard for orthodonic force.The treatment result is overly dependant on the physician level,which is easy to cause injury to the patients and reduce the efficiency of treatment.Therefore,establishing a parametric prediction model of orthodontic force and analyzing the effect of orthodontic force are very necessary for developing dental digital diagnosis and treatment,and assisting doctors to improve the safety and foresight of orthodontic treatment.This paper has carried out the following research in the following aspects.The prediction model of orthodontic force of functional loop and sequential loop is established.The two basic loading units of functional loop and sequential loop are selected as the main research objects.Based on the idea that the orthodontic force is determined by the deformation state of the archwire,the characteristic parameters,material parameters and section parameters of the two kinds of loop are extracted as effective parameters of the model.The relationship between the orthodontic force and the parameters is analyzed by using the equivalent beam deformation theory by analyzing the structural characteristics of the loop.The correction coefficient is introduced to eliminate the influence of the inherent error.The parameterized expression of the orthodontic force is realized.The experimental measurement and finite element simulation of the orthodontic force of functional loop and the orthodontic force of the sequential loop under different parameters are carried out.According to the loading characteristics of the functional loop and the sequential loop,we design the orthodontic force measuring device of functional loop based on the single sensor and the orthodontic force measuring device of sequential loop based on the six dimensional sensor.According to the open vertical loop,the sequential loop of root pressing and the rotation around the cheek-tongue direction,the corresponding measuring method is designed and a comparative experiment is carried out according to the influence parameters.The finite element models of the functional loop and sequential loop are established,and the orthodontic force of under each modle is analyzed by the statics module of Workbench by comparing the experimental results with the calculation results of the prediction model without considering the correction coefficient,a mathematical model of correction coefficient is obtained,and a complete orthodontic force prediction model is established,and the accuracy of the model is verified.By comparing the experimental results and simulation results,the feasibility of the proposed orthodontic force simulation method is verified.Taking the lower maxillary incisors as an example and the orthodontic forces along the near-far middle direction,the orthodontic forces along the crown-root direction and the orthodontic moment around the tongue-cheek direction as loading condition,the biomechanical simulation of the tooth is carried out by the method of finite element simulation.The CT images of the skull are segmented and denoised by Mimics.The solid models of teeth,periodontal ligament,alveolar bone and brackets are established by Gomagic and Solidworks.The material characteristics of the periodontal ligament are defined by the two order Ogden hyperelastic model.Taking the periodontal ligament capillary pressure as a criterion for orthodontic safety,combined with the stress response of periodontal ligament,the safe orthodontic force range of mandibular central incisors is obtained.By analyzing the displacement of the teeth in different directions,the moving types of the mandibular incisors under different orthodontic forces are determined.