The Biomechanical Research Of Dental Tissue With Spee-curve Arch Wire

Malocclusion is a widespread oral malformation of modern people, the main performance is the disorder arrangement of tooth, the disorder occlusion of upper and lower dental arch, the incoordination of the relation position and size of maxilla and mandible, skull,etc.It is the relatively complex symptom in the orthodontics clinic, and will seriously affect sufferer's jaw system, particularly chews and the language function will be seriously damaged; It also gives sufferer's body and mind grave effect. Recently years "Spee-curve arch wire"have been used is one kind of Straight arch wire in the orthodontics clinical at home and abroad, it is often used to trim Spee curve and open the bite. As the development of Straight arch wire correcting technique, "Spee-curve arch wire"has been widely used. This dissertation studies on the biomechanical research of dental tissue with "Spee-curve arch wire", which use synthetically test stress analysis and theory stress analysis that is finite element method in the oral-mechanics. The first section applies electrometric method. It studies the difference type, the difference material and distinct radians of "Spee-curve arch wire"in the orthodontics clinic. Arch wire is put on the standard model of tooth, separately measure the force loading in the anterior teeth and molars with arch wire. Comparing the force loading in the anterior teeth and molars with 0.016 ×0.022'' MEAW in the orthodontics clinic and observing the variety of the force value, search for the optimum type, material and radians "Spee-curve arch wire"applicable to treats malocclusion. Test finds that "Spee-curve arch wire"which are made of 15 °, 20 °0.016''stainless steel are same to the force of teeth conduced by 0.016 ×0.022'' MEAW , so on clinical sufferer are proposed employ these arch wire. The second section applies 3-D reconstruction technology to build 3-D solid model of dental tissue. Appling the method of CT image processing and according to screw CT (Philips Mx8000) applied by department of malocclusion, second hospital of JLU, it has been builded by using the CAD software of SolidWorks. The concrete step is as follows: (1) Choose the position of CT fault scans. The basic principle of seat firstly to choose CT's fault scanning should be: Not to lose, and does not distort the shape form structure size information of living things structures, and try best to reduce the section number, and pay attention to sampling arrives footstep, sharp and part top, part key seats such as bottom, maximum diameter place and minimal diameter place, as well as some transition seats, etc. (2) Abstraction of the edge coordinate. Firstly, abstract of the edge. CT image is two-dimentional grey level image, it could be image processing by photoshop software, strengthen and draw with the edge. Finally, check up the characteristic point on the edge. In order to calculate convenient and improve computational speed, it is unnecessary to check up all points on the edge, and need only use several key points. Carry on the coordinates of key points, and exists side by side for the file. (3)Using the spline curve to draw up among the marginal data of the edge drawn up and will bring into being of contour read in SolidWorks, will each level number according to the read in, the wire frame picture of formation model. (4) The formation of solid model. The angle of from characteristic aspect is seen, and the characteristic that SolidWorks2003 can constitute has the drawing aspect to become two kinds of drawing aspect with the layer. The drawing aspect is called the cylinder again, and is the section shape form and the characteristic of dimension unchangeableization, is the equal section aspect. Like cylinder and prism. The layer becomes the drawing aspect to beserved as to become the section aspect , and the dimension and shape form of his horizontal section all can occur changing . Containing the characteristic aspect that has the free curved surface is that the layer becomes one kind of the drawing aspect. The result show that the three-dimensional finite element modeling method to originally adopt in the article is accurate and feasible, the model built have better comparability of mechanics and geometry. The data included among them can do preliminary mandible and tooth stress analysis, it is suitable for various kinds of three-dimensional finite element analysis in orthodontics. The third section applied software CosmosWorks to three-dimensional finite element analyze the dental tissue loading in orthodontic forces. CosmosWorks and SolidWorks does not have the integrated finite element analysis software, and carries it on the establishment of living things mechanics finite element models with SolidWorks, it can fully use the quick and big and powerful and accurate characteristic of CosmosWorks. In the finite element model, the characters of periodontal membrance's, mandible and teeth are nonlinear, anisotropic and so on, so mechanical parameter is not easily confirmed. In this dissertation periodontal membrance and tooth are assumed isotropy to short-cut calculation scale; mandible is anisotropic, the whole anisotropic independence elastic modulus is 21, and many parameters yet not acquire at the moment, and still very hard acquire in practice. Orthotropic reduces elastic modulus 9, make known anisotropic in the degree, and it is more practicable, obtains parameter easily, and the pattern mechanics similarity lift the one-step. Load condition is designed according to various kinds of orthodontic forces in "Spee-curve arch wire"correcting malocclusion. Operating mode 1 is Class Ⅲshort vertical elastic; operating mode 2 is Class Ⅲlong elastic; operating mode 3 is ClassⅡshort vertical elastic; operating mode 4 is ClassⅡ...