The Three-dimensional Finite Element Analysis Of Different Depth Of Beta Titanium Reverse-curve Archwires On The Vertical Force Exerted To The Mandibular Teeth

Objective:With the method of three-dimensional finite element analysis, the study was to analyze the vertical force on mandibular teeth produced by different depth curve of rectangular beta titanium reverse-curve archwires.Method:The three-dimensional finite models of mandibular alveolar bone and teeth, as well as 2mm,4mm and 6 mm depth of 0.017×0.025 inch rectangular beta titanium, NiTi and stainless steel reverse-curve archwires, were set up with the application of MIMICS and I-DEAS software. Import these models to ABAQUS software.Establish the displacements of deformation of the reverse-curve archwires on the models, and calculate the vertical force of different depth of 0.017x0.025 inch rectangular beta titanium, NiTi and stainless steel reverse-curve archwires on each mandibular tooth, as well as the vertical force on mandibular teeth produced by the rectangular beta titanium reverse-curve archwires after extracting the lower first premolar.Result:1. When the depth curve is 2 mm, the vertical force on mandibular teeth produced by 0.017×0.025 inch rectangular beta titanium reverse-curve archwire is 0.023-0.105N,rectangular NiTi reverse-curve archwire is 0.009-0.046N,rectangular stainless steel reverse-curve archwire is 0.055-0.291N.When the depth curve is 4 mm, the vertical force on mandibular teeth produced by 0.017×0.025 inch rectangular beta titanium reverse-curve archwire is 0.035-0.145N,rectangular NiTi reverse-curve archwire is 0.021-0.076N,rectangular stainless steel reverse-curve archwire is 0.093-0.404N.When the depth curve is 6 mm, the vertical force on mandibular teeth produced by 0.017×0.025 inch rectangular beta titanium reverse-curve archwire is 0.128-0.257N,rectangular NiTi reverse-curve archwire is 0.043-0.138N, rectangular stainless steel reverse-curve archwire is 0.268-0867N.2. With the increase of depth of the reverse-curve archwires, the vertical force on mandibular teeth is increased except lower canine. The vertical force on mandibular teeth produced by 0.017x0.025 inch rectangular beta titanium and NiTi reverse-curve archwire are all less than 0.34N. The vertical force on lower first molar produced by 4 mm depth of 0.017×0.025 inch rectangular stainless steel archwire is 0.404N, while the vertical force on other teeth are less than 0.34N. The vertical force on mandibular teeth produced by 6 mm depth of 0.017x0.025 inch rectangular stainless steel archwire are larger than 0.34N, except lower canine.3. The vertical force on incisors and first molar produced by the rectangular beta titanium reverse-curve archwire didn't change significantly after extracting the lower first premolar. The force on canine produced by the 2mm depth of rectangular beta titanium reverse-curve archwire decreased after extracting the lower first premolar, while increased significantly by 4 mm and 6mm depth. However. The force on second premolar produced by the 2mm and 4mm depth of rectangular beta titanium reverse-curve archwire increased significantly after extracting the lower first premolar, while decreased by 6mm depth.Conclusion:1. When the depth of rectangular beta titanium reverse-curve archwire is 2mm, the maximum vetical force is on canine, and the minimum on second premolar. When the depth is 4mm, the maximum vetical force is on first molar, and the minimum on central incisor. When the depth is 6mm, the maximum vetical force is on second premolar. and the minimum on canine.2. The vertical force on mandibular teeth produced by 2mm.4mm and 6mm depth of 0.017×0.025 inch rectangular beta titanium reverse-curve archwire is applicable to orthodontic treatment.3. The effect of opening the bite by rectangular beta titanium reverse-curve archwire is better than NiTi, and weaker than stainless steel,while the force produced by beta titanium reverse-curve archwire is milder than stainless steel.