Do you know about NiTi alloy wire?
1940, gold arch wire, cobalt-chromium alloy wire and stainless steel round wire. In 1960, martensitic stabilized alloys: mostly made of nickel-titanium alloys deformed in the martensitic state. This type of archwire has low stiffness and can produce lighter correction force. There is no martensitic transformation caused by stress or temperature, so there is no memory effect or superelasticity. In 1980, Chinese nickel-titanium alloy and Japanese nickel-titanium alloy archwires were austenite-activated alloys: that is, they showed an austenite state in any state and did not have a martensitic state caused by temperature when placed inside or outside the mouth. , the martensitic state can only be caused by stress and has superelasticity, but does not have shape memory function. This type of archwire has excellent resilience and low stiffness, and can produce weak correction force. The characteristic of Zuoda is that the force it generates is constant from the initial start to the final stage, and the effect is better when treating early uneven teeth. The disadvantage is that it cannot be bent into shape at room temperature and is not easy to weld. If this company is used as the main archwire, it can often cause undesirable arch expansion or contraction, and it will be difficult to establish good premolar and molar alignment.
In 1990, martensite-activated nickel-titanium alloy: that is, the TTR is lower than the oral temperature or very close to the oral temperature. It exists in a multi-element state at room temperature and is easy to deform. When placed in the oral cavity, it is caused by stress and room temperature. The martensite transforms into austenite at the same time, that is, there is shape memory function and superelasticity. It is easy to deform at room temperature (around 25°C) and below, but when it reaches a certain temperature (around 32°C), it will return to its original preformed shape, showing shape memory and superelasticity characteristics. The Smart brand of Beijing Shengmart Technology Co., Ltd. and the NitinolHA brand of 3M Company are both typical representative products. Because of this characteristic, the heat-activated nickel-titanium archwire can be easily manipulated and molded by maintaining it at normal temperature and below, and placed in the bracket. When activated by warm heat in the oral cavity, it can produce Shape recovery ability and provides the required strength for orthopedics. Because the heat-activated nickel-titanium orthopedic wire has the characteristics of "softening when exposed to cold and becoming elastic when activated by heat", patients can change the orthodontic force by holding cold or hot water in their mouths under the guidance of a doctor, making it more flexible. It facilitates correction by the orthodontist and reduces the discomfort of initial correction. Added thermodynamic nickel-titanium alloy: The TTR temperature is higher than the oral temperature, about 40°C. In this way, when the nickel-titanium archwire is placed in the oral cavity, it is still in a multi-dimensional state, and the archwire is relatively soft. When hot water is held in the mouth , there is austenite transformation. Therefore, the orthodontic force is weaker and can be used as an initial archwire for adult patients and patients with periodontal disease. The copper-containing nickel-titanium wire produced by Omcro and Japan's low-lag L-H nickel-titanium archwire have this performance.
Clinical applications of nickel-titanium alloy wire:
1. Nickel-titanium spring: Nickel-titanium push spring and tension spring are springs used in orthodontics. They have the special properties of nickel-titanium superelasticity and are suitable for orthodontic treatment to open up the gaps between teeth and pull teeth in different directions. A nickel-titanium coil spring can produce approximately 50g of force when stretched 1mm. Nickel-titanium coil springs have high elastic properties and can produce softer and more stable sustained force in the stretched state. The force attenuation is very small, and it can produce ideal orthodontic force that meets the clinical needs of moving teeth. Meet physiological requirements. Nickel-titanium wire tension springs have high elasticity and extremely low permanent deformation rate. Compared with stainless steel wires of the same diameter, the correction force released is 3.5-4 times different. Therefore, in the application of orthodontic treatment, patients not only have less pain, but also feel soft and lasting strength, and the time for follow-up visits is reduced, the course of treatment is shortened, and the efficacy is improved. It is a new and excellent mechanical device in orthodontic treatment.
2. Used for early alignment and leveling of the patient's dentition. Due to the superelasticity and shape memory properties of nickel-titanium alloy archwires and the low stress-strain curve, nickel-titanium alloy archwires are currently routinely included in the orthodontic system as the initial stage in clinical practice. arch wire, so that the patient's discomfort will be greatly reduced. Since there are currently several different straight wire arch correction technologies, MBT technology recommends the use of 0.016-inch heat-activated nickel-titanium alloy arch wire (HANT wire), and DEMON self-ligating bracket technology recommends the use of copper-containing heat-activated nickel-titanium alloy produced by Omcro. Alloy arch wire (phase transition temperature is about 40 degrees), O-PAK orthodontic technology recommends the use of 0.016-inch super-elastic nickel-titanium alloy arch wire for early alignment and leveling.
