The application of titanium nickel memory alloy in medical treatment

       

The application of titanium nickel memory alloy in medical treatment

The two characteristics of titanium-nickel alloys after different treatments have their own characteristics. Applying this characteristic to medical treatment will be made into medical sutures. According to the clinical suture requirements, it can be sutured without damage to muscles and skin. Shaped usable temperature memory metal suture thread, and can use super-elastic metal suture thread that does not need to be shaped. After the wound is healed, the metal thread is drawn out so that no foreign body is left in the human body, so that the wound will not appear hard edges, pinholes and other bad conditions. A medical product without injury after surgery.

 

Special properties of Nitinol:

 

Shape memory characteristics (shape memory) shape memory is when the parent phase of a certain shape is cooled from above Af temperature to below Mf temperature to form martensite, the martensite is deformed at a temperature below Mf, and heated to below Af temperature, accompanied by reverse phase Change, the material will automatically restore its shape in the parent phase. In fact, the shape memory effect is a thermally induced phase transformation process of Nitinol.

 

Superelastic (superelastic) The so-called superelasticity refers to the phenomenon that the sample produces a strain much larger than the elastic limit strain under the action of external force, and the strain can automatically recover when unloaded. That is, in the state of the parent phase, due to the action of the applied stress, the stress-induced martensitic transformation occurs, so that the alloy exhibits a mechanical behavior different from that of ordinary materials. Its elastic limit is much greater than that of ordinary materials, and it is no longer obeyed. K’s law. Compared with shape memory properties, superelasticity has no thermal involvement. In a word, superelasticity means that the stress does not increase with the increase of strain within a certain deformation range. Superelasticity can be divided into linear superelasticity and nonlinear superelasticity. In the former stress-strain curve, the relationship between stress and strain is close to linear. Nonlinear superelasticity refers to the result of stress-induced martensitic transformation and its reverse phase transformation during loading and unloading in a certain temperature range above Af. Therefore, nonlinear superelasticity is also called phase transformation pseudoelasticity. The phase change pseudo-elasticity of Nitinol can reach about 8%. The superelasticity of nickel-titanium alloy can change with the change of heat treatment conditions. When the archwire is heated to above 400oC, the superelasticity begins to decrease.

 

Sensitivity to temperature changes in the oral cavity: the orthodontic power of stainless steel wire and CoCr alloy orthopedic wire is basically not affected by the temperature in the oral cavity. The corrective force of the super-elastic nickel-titanium alloy orthopedic wire changes with the change of the oral cavity temperature. When the amount of deformation is constant. As the temperature rises, the correction power increases. On the one hand, it can accelerate the movement of teeth. This is because temperature changes in the oral cavity will stimulate the blood flow at the stagnant blood flow caused by the orthodontic device, so that the repair cells are fully nourished during the tooth movement. Maintain its vitality and normal function. On the other hand, orthodontists cannot precisely control or measure the orthodontic force in the oral environment.

 

Recently, there is a non-traumatic cosmetic skin suture needle. The characteristic of the needle is that a titanium-nickel memory alloy wire is connected to the tail of the suture needle as a suture thread, and it is plated with metallic zinc. Because the memory alloy wire has temperature memory, it forms a straight line when it reaches the original set temperature, showing the elastic properties of metal materials, which are not available in general metal materials. This method is used to suture the skin to make surgical wounds The healing is ideal.

 

Suture shaping and muscle binding are achieved. Suture shaping and muscle binding use the various suture needles mentioned above, using stitch removal and joint binding, and pull out the metal wire in the healing wound like a straight line. No foreign body remains in the body. The characteristics of being able to pull out the metal wire are the temperature memory of the metal and the superelasticity that is not affected by temperature.