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Continuous advances in medical technology have extended human lifespan. New advances have been made with the development of new uses for metal-grade alloys in outdoor and indoor applications. What are the special properties of medical nitinol guidewire?

What are the special properties of medical nitinol guidewire?

1. Shape memory: shape memory refers to the fact that when the parent phase of a certain shape is cooled from above the Af temperature to below the Mf temperature to form martensite, the martensite is deformed below the Mf temperature, and after heating below the Af temperature, the material will automatically restore its shape in the parent phase with an inverse phase transformation. In fact, the shape memory effect is the thermally induced phase transition process of NiTi alloys.

2. Superelasticity The so-called superelasticity: refers to the phenomenon that under the action of external force, the strain of the specimen is much greater than the elastic limit strain, and the strain can be automatically recovered during the unloading process. That is, in the parent phase state, due to the action of external stress, a stress-induced martensite phase transition occurs, so that the alloy exhibits different mechanical behavior from ordinary materials, and its elasticity limit is much greater than that of ordinary materials, and Hooke's law is no longer observed. In contrast to shape memory properties, superelasticity has no thermal involvement.

3. Sensitivity to temperature changes in the mouth: The orthodontic force of stainless steel wire and CoCr alloy orthodontic wire is basically not affected by the temperature in the mouth. The orthodontic force of superelastic NiTi alloy orthodontic filament changes with the change of oral temperature. When the deformation does not change. The higher the temperature, the greater the orthodontic force. On the one hand, it can speed up the movement of teeth, because the temperature change in the mouth will stimulate the blood flow in the stagnant part of the blood flow caused by the orthodontic device, so that the repair cells can obtain sufficient nutrients during the tooth movement process to maintain their vitality and normal function. On the other hand, orthodontists cannot precisely control or measure orthodontic force in the oral environment.

4. Corrosion resistance: Studies have shown that the corrosion resistance of nickel-titanium wire is similar to that of stainless steel wire.

5. Anti-toxicity: Ni-Ti shape memory alloy has a special chemical composition, that is, it is an atomic alloy such as Ni-Ti, containing about 50% Ni, which is known to have carcinogenic and carcinogenic effects. In general, the oxidation of titanium in the surface layer acts as a barrier, making Nitinol alloy have good biocompatibility. TiXOy and TixNiOy on the surface inhibit the release of Ni.

6. Soft orthodontic force: At present, the commercial orthodontic wires include austenitic stainless steel wire, cobalt chromium-nickel alloy wire, nickel-chromium alloy wire, Australian alloy wire, gold alloy wire, titanium alloy wire. About the load-displacement curve of these orthodontic filaments under tensile test and three-point flexure test conditions. Nitinol has a low, flat unloading curve plateau, indicating that it provides long-lasting, mild orthodontic force.

7. Good shock absorption characteristics: the greater the vibration of chewing and bruxism on the archwire, the greater the damage to the tooth root and periodontal tissue. According to the results of different bowwire attenuation experiments, it is found that the amplitude of stainless steel wire is greater than that of superelastic NiTi wire, and the initial amplitude of superelastic NiTi archwire is only half of that of stainless steel wire. The good vibration and shock absorption properties of bowwires are very important for the health of teeth, while traditional archwires such as stainless steel wires tend to increase root resorption.