A Finite Element Analysis Of Distal Movement Of Canine With Invisible Appliance

BackgroundWith the rapid development of Orthodontics, orthodontic appliance has also undergone great changes from the edgewise appliance in 1926, to the straight wire appliance later, with the improvement of living standards, and with the great progress of the science of computer aided technology and material science, an invisible appliance has been increasingly commomly used in the last 20 years. Invisible appliances progress is limited by hot film material. Compared with fixed appliance,invisible appliance are not good at the root control. As the uncomparable advantage of’invisible’ look,an endless stream of a variety of academic research is seeking for the mechanism of orthodontic tooth and loading pattern,and the approach to solve the shorts. Finite element analysis, as a theoretical analysis,has already been commonly used in the application of the orthodontic subjects. This chapter is an finite element analysis of canine distal movement with invisible appliance. Clinically by adding attachments on the crowns,it can be more effective to control the movement of teeth. By constructing canine, alveolar bone and periodontal ligament-the invisible appliance three-dimensional finite element analysis model, after adding attachment on the crown of the canine, we expect to explore the possibilities of using the finite element analysis to design the attachment.MethodsThe 3 Shape scans the tooth model in vitro to get the teeth STL scan data,and then import the data into the rhino software for Boolean operations division, to obtain periodontal membrane model, model of alveolar bone, no bracket invisible appliance model.Finally, alveolar bone and periodontal ligament-canine invisible appliance model is established through boolean assembly. Derived sat data to ABAQUS software for nonlinear contact analysis, carrying out finite element analysis of canine alveolar bone and periodontal ligament-invisible appliance.Import the data into the software rhino, adding a vertical rectangular 3*2*1mm annex in the center of clinical crown of canine. After fusion of the sticky attachment, expand 0.75mm in the normal line direction of the crown surface normal direction to get invisible appliance. Then we would be able to obtain the alveolar bone-periodontal tissue-canine-invisible appliance model.ResultsBy forcing displacement from invisible appliance in canines, we get the model with 71699 units and 105502 nodes.The analysis shows that the stress focuses on the gingival side of appliance, and the upper 2/3 of the canine root,the invisible appliance is appearing tracking off,and the tooth shows tipping movement. Adding the vertical rectangular attachment in canine, the appliance seems to be better tight to the canine. The force seems to concentrate in the gingival edge of invisible appliance. And the stress is more evenly distributed in the root surface, fangs tend to move orderly.ConclusionsThe construction of alveolar bone-periodontal tissue-canine-the invisible appliance model is of a high degree of simulation. Through the finite element analysis, we come to the conclusion that invisible appliance shall be fixed by adding attachments. Also, the attachments can adjust the force of teeth and control the movement style of the teeth. By adding attachments in vitro, parallelly biomechanical analysing the movement of invisible appliance with finite element method is feasible. Vertical rectangle attachment is able to enhance the retention effect of invisible appliances, and it help effectively move the canine in a orderly style.