That is to say, in the parent phase state, due to the external stress, the stress-induced martensite transformation occurs, so the alloy shows different mechanical behavior from ordinary materials, its elastic limit is far greater than that of ordinary materials, and it no longer obeys Hooke's law. In contrast to shape memory properties, superelasticity is not thermally involved. In a word,nickel titanium wire, hyperelasticity means that the stress does not increase with the increase of strain within a certain range of deformation, and the clinical manifestation is that the orthodontic force generated by the archwire in the process of deformation remains constant and no longer gradually loses with the movement of teeth towards the orthodontic direction. According to the characteristics of the stress-strain curve corresponding to hyperelasticity, hyperelasticity can be divided into two types: linear and nonlinear hyperelastic. In the stress-strain curve of the former, the relationship between stress and strain is nearly linear. Nonlinear hyperelasticity is the result of stress-induced martensitic transformation and its reverse transformation during loading and unloading in a certain temperature range above Af, so nonlinear hyperelasticity is also called phase transformation pseudoelasticity. The phase transformation pseudoelasticity of NiTi alloy can reach about 8%. The superelasticity of nitinol can vary with the conditions of heat treatment, and begins to decrease when the archwire is heated above 400ºC. When the heat treatment temperature exceeds 600ºC, the superelasticity is substantially small. According to this characteristic, the non-orthodontic area of the archwire can be thermally treated to lose its superelasticity in clinic, so as to avoid the influence of the orthodontic process on the teeth in the non-orthodontic area, while the archwire in the orthodontical area still has good elasticity. 3. Sensitivity of temperature change in oral cavity: The orthodontic force of stainless steel wire and CoCr alloy orthodontic wire is basically not affected by the temperature in oral cavity. The orthodontic force of the superelastic NiTi alloy orthodontic wire varies with the oral temperature. When the amount of deformation is constant. The orthodontic force increased with the increase of temperature. On the one hand, it can accelerate the movement of teeth, because the temperature change in the oral cavity will stimulate the blood flow in the blood stasis area caused by the capillary stagnation caused by the orthodontic device,titanium sheet grade 5, so that the repair cells can be fully nourished during the movement of teeth to maintain their vitality and normal function. As a result, some physicians have switched to using a rocking-chair nickel-titanium archwire, which is similar to the mechanical system, with vertical traction of the anterior teeth. Although this has a similar effect, it is felt that when compared with MEAW, the movement of each independent tooth is not as good as that of MEAW technology. The reason is that the rocking-chair nickel-titanium archwire is a continuous archwire, and there is no way to bend it. Therefore, the angle of the bracket bonding and the rocking curvature of the archwire determine the angle of each tooth,Titanium welding pipe, unlike the MEAW technique where there is room for individual adjustment of the angle of each tooth. Use the LH nickel titanium to bend the rocking chair, and then use the arch wire shaper to bend back or forward in the mouth, the effect is quite ideal. Return to Sohu to see more Responsible Editor:. yunchtitanium.com