Original Title: Clinical Application of Nitinol Wire Clinical Application of Nickel-Titanium Alloy Wire 1. It is used for the early alignment and leveling of the patient's dentition. Due to the superelasticity, shape memory performance and low stress-strain curve of the nitinol arch wire, the nitinol arch wire is routinely used as the initial arch wire in the orthodontic system in clinic at present, so that the discomfort of the patient will be greatly reduced. Because there are several different straight wire technique, that MBT technique recommends the use of 0.016 inch heat-activated nitinol archwire (Hant wire), and the DEMON self-ligating bracket technique recommends the use of copper-containing heat-activated nitinol archwire produced by Omcro company (the phase transition temperature is about 40 degrees). The O-PAK technique recommends the use of a 0.016 inch superelastic Nitinol archwire for early alignment and flattening. 2. Nickel-titanium spring: Nickel-titanium push spring and tension spring are a kind of spring used for orthodontics. They have the characteristics of nickel-titanium superelasticity and are suitable for orthodontics to open up the gap between teeth and pull teeth in different directions. An extension of 1 mm of the nickel-titanium coil spring produces a force of approximately 50 G. The nickel-titanium coil spring has high elastic performance, and can generate soft and stable continuous force in a stretching state. The attenuation of the force is very small, and an ideal orthodontic force which meets the requirements of clinical tooth movement can be generated. Meet the physiological requirements. The nickel-titanium wire tension spring has high elasticity and extremely low permanent deformation rate, and compared with the stainless steel wire with the same diameter, the correction force released by the nickel-titanium wire tension spring is 3.5-4 times different. Therefore, in the application of orthodontic treatment, patients not only feel less pain, feel soft and lasting strength, but also reduce the return visit time, shorten the course of treatment, improve the curative effect, which is a new and excellent mechanical device in orthodontic treatment. 3. L-H archwire is a Japanese Dr. Developed by Soma and others and produced by Tomy. LH "is named" Low Hysteresis "meaning that when the archwire is ligated to the bracket, the stress generated when the archwire is activated" is very close to the stress generated when the tooth is moved, that is, the archwire slowly returns to its original state. I.e. The lag is small. SOMA et al. compared the stress-strain curves of LH archwire and other nickel-titanium alloy archwires. The hysteresis range of L-H archwire is the smallest, which makes the archwire have the advantages of low load and sustained light force. At the same time, the initial slope of the curve is low, indicating that the archwire has low stiffness. The hysteresis curves of other types of nickel-titanium alloy archwires show that they are more rigid. Obviously, L-H archwires have obvious mechanical advantages. Because the proportion of titanium in nickel-titanium LH wire is higher than that in general nickel-titanium arch wire, it is called titanium-nickel wire, and experiments have proved that its shock-absorbing effect is stronger. The LH nickel-titanium wire is also characterized in that the LH nickel-titanium wire can be bent and can be heated and shaped by using a heat treatment instrument, so that the treatment can be finished by arranging and leveling the LH nickel-titanium wires, opening the occlusion, closing the gap and finishing the treatment with one upper arch wire and one lower arch wire respectively, as long as the arch wires are taken out to be bent into a required shape at each stage and shaped by using the heat treatment instrument, The hardness can be strengthened. At present, the L-H archwire is used clinically for the treatment of maxillary expansion, correction of open jaw, partial jaw and cross jaw, because of its continuous stability and softness of strength, the effect is better. At the same time, J hook is often used to improve the deficiency of soft arch wire. Although the MEAW technique is ideal for the correction of the above malocclusion, nickel titanium wire , the complicated bending of the archwire often deters many physicians. Expand the full text 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, 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. Although I am often exposed to the term of thermal activation, I know little about it. I have consulted the relevant knowledge in a book, hoping to increase our understanding of thermal activation of nickel-titanium wire. There are two main aspects to describe the hardness of nickel-titanium wire. Martensitic state refers to the state with the softest arch wire and the highest bending degree. Austenitic state refers to the hardest state of the arch wire. This is the state of the archwire at room temperature. The arch wire in martensitic state will change into austenitic state when it is heated, which is called thermal activation. Although similar changes occur in archwires in the austenitic state, the degree of change is smaller and almost imperceptible. The arch wire in martensitic state has much better elasticity than that in austenitic state, that is, it has a strong ability to recover to the original shape after deformation, and it is not easy to be broken; while the force generated by the arch wire in austenitic state is 42% higher than that of the arch wire in martensitic state, but the force released by the arch wires in martensitic-state is more durable and constant. The elastic deformation ability of the two archwires is similar, but the archwire in the Martensite state can be temporarily deformed at room temperature and can be restored to the original shape at oral temperature, thereby greatly improving the actual deformation range of the archwire. Thermally activated archwires are ideal for the early stages of treatment and are suitable for use as initial archwires because of their wide range of practical deformation and their gentle and durable force. In theory, it can be fully seated in the bracket of a severely malpositioned tooth. Both round and rectangular archwires can be used as initial archwires. Advantages of thermally activated nickel titanium wire: 1. Less pain for patients: This results from a gradual increase in force and eventually a light force. The controlled thermal activity prevents a sudden increase in force when eating hot drinks or hot food. The patient can relieve the excessive force by drinking cold water. 2. Brackets fall off and ceramic brackets break less: This is due to the gradually increasing light force. Such archwires are ideal for ceramic brackets. The archwire can maintain its martensitic state at low temperature, which helps to further reduce the initial force value and make the placement of the archwire easy. 3. Less arch wire breakage: Because it is softer than the austenitic arch wire, it is not easy to break after being stressed. 4 Reduced chair-side working time: Because of its large deformation range, it can reduce the adjustment times and the replacement times of the arch wire. 5. Shortening of treatment time: Preliminary studies have shown that early torque control and the use of light and sustained force can shorten the total treatment time, and the early use of rectangular wires in straight wire brackets can directly move the teeth to the ideal position. Shortcoming It can not effectively maintain the shape of the dental arch, and it is better not to use it to close the gap, because the force of the elastic ring and coil spring will deform the arch wire and tilt the teeth. In addition, although heat-activated nitinol wires can shorten chair-side working time, the time to move teeth is longer, and doctors should wait patiently for the archwire to fully play its role. Objective To compare the stiffness, elasticity, strength and fatigue resistance of Australian wire, American orthodontic wire, imitated Australian wire, domestic stainless steel wire and heat-treated domestic stainless steel wire, and to provide the basis for clinical rational selection of orthodontic wire. Methods The mechanical property of five kinds of orthodontic wires were tested and compared, including elastic modulus, elastic limit, rebound angle, tensile strength,titanium sheet grade 5, torsion strength and fatigue strength. Results The stiffness, elasticity, strength and fatigue resistance of five kinds of orthodontic wires were compared. Conclusion The steel wire should be selected according to the demand of different orthodontic time and the different characteristics of steel wire in clinic. Contact us Back to Sohu to see more Responsible Editor:. yunchtitanium.com
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