Research On Virtual Orthodontic Path Planning Method

Virtual orthodontic system is the core of digital orthodontics.It realizes the way and steps of tooth movement in 3D visualization state,including single tooth segmentation and repair,tooth movement and orthodontic scheme formulation,gingival tissue deformation and accessory installation and fusion.The ultimate goal is to provide digital 3D model for invisible appliance.The determination of tooth movement trajectory and orthodontic treatment plan is a very important technical link in the virtual orthodontic system.It not only enables patients to see the virtual treatment effect before orthodontic treatment,but also facilitates doctors to design orthodontic treatment plan and predict the effect of orthodontic treatment.Accurate movement path planning and reasonable orthodontic treatment can reduce the pain of patients,reduce the dependence on the experience of dentists,and improve the orthodontic experience of patients.The main contents and innovations are as follows.(1)Orthodontic path planning is an obstacle problem of multi-objective and multi constraint path planning.Aiming at the complex orthodontic movement,this paper realizes orthodontic path planning by improved multi particle swarm optimization algorithm when the initial and target pose of teeth are known.Firstly,the constraint conditions and optimization objectives of tooth movement are modeled;Secondly,set the priority of teeth and select OBB bounding box to simulate tooth collision detection;Finally,on the basis of particle swarm optimization,the inertia parameters,the upper and lower limits of position update and the speed update strategy are improved to improve the clinical applicability of the path planning algorithm and shorten the orthodontic path.(2)In view of the situation that the teeth can not reach the ideal posture due to the lack of efficiency of invisible appliance,this paper analyzes the movement efficiency of teeth in different movement dimensions,corrects the movement results through the way of path compensation,proposes two overcorrection methods and evaluates them;finally,selects the pre overcorrection method to generate orthodontic scheme,visualizes the orthodontic movement process,and compares the effect before and after overcorrection,so as to improve the orthodontic effect Virtual orthodontic process is more perfect.(3)The improved multi particle swarm optimization orthodontic path planning algorithm is simulated on the MATLAB platform.The length of orthodontic path is reduced by about 10%and the rotation angle is reduced by 7%compared with before.The algorithm shows good performance and clinical adaptability.In the visualization experiment,the orthodontic movement process and orthodontic effect before and after overcorrection are displayed.