Titanium nickel alloy medical nickel alloy wire, according to clinical need, through adjusting the proportion of titanium alloy, with different process, produced to different degrees of mechanical performance and specifications of the wire, if needs to be some place setting in use, the wire can be made into temperature memory performance sutures, if do not need to help setting on the use, the wire can be made into is not affected by temperature to exceed elastic properties of the suture line.

The medical applications of memory alloys are very attractive.

Such as:

The plate not only holds the two broken bones in place, but also produces compression force during the process of restoring the original shape, forcing the broken bones to join together.

Dental orthodontic wire, long clips for ligating cerebral aneurysms and vas deferens, and struts for spinal straightening are all activated by body temperature after implantation. Thrombus filter is also a new product of memory alloy. When the straightened filter is inserted into the vein, it gradually returns to a network, preventing 95% of clots from reaching the heart and lungs.

Recently, with the development of medical biomaterial science, combined with the clinical medical needs, niti shape memory alloy because of its shape memory effect, and has high strength, wear resistance, corrosion resistance, non-magnetic, non-toxic, such as excellent physical and chemical properties, hardness and stiffness and bone tissue close to the human body, is considered to be one of ideal biological fixation implant materials, obtained widespread application in the medical field. Currently reported niti shape memory alloy in the field of medical application in orthopaedics, dental, thoracic surgery, obstetrics and gynecology, and image subject, etc., has developed products have scoliosis hartz rods, hip prosthesis, within the frame type foot radius holder, patella holder, an iud in uterus, dental orthodontic wire and other biomedical materials.

Most biological compatibility study of niti shape memory alloy has lower cell and genetic toxicity, but due to the large amounts of nickel in the process of the niti shape memory alloy elements exist, and a potential toxicity to human body, nickel and its compounds and excessive nickel ions existing human body may cause allergic reactions, local tissue after nickel ions into the fluid circulation may also affect the metabolism of amino acids, proteins, metamorphism, opposite and an adverse effect on blood system, which in turn lead to birth defects, cancer and other adverse consequences. Therefore, the safety of nickel-titanium shape memory alloy has been concerned by researchers. Niti shape memory alloy in the human body will have nickel ion precipitation, and its release quantity and alloy surface roughness and chemical composition are closely related, nickel ion release quantity and its toxic effects on the body has become the limiting factor of alloy applications, there are a lot of scholars by modifying the surface of niti shape memory alloy to expect the purpose of improving alloy biocompatibility. This paper intends to review the niti shape memory alloy biocompatibility related research progress, from in vitro cell test, animal test, clinical application and the effect of surface modification on its biocompatibility aspects were reviewed, and objectively evaluate the biocompatibility of the niti shape memory alloy and the necessity of surface treatment to improve its biocompatibility. Research progress on biocompatibility in vitro the dissolution of nickel ions in niti shape memory alloy implants has attracted much attention. Many researchers have monitored the release of nickel ions in niti shape memory alloy. For example, in the study of dissolution of niti shape memory alloy wire in vitro, researchers found that the average release rate of nickel ions was 13.05mg/ d, significantly lower than the average dietary intake of 200-300mg/ d. In another study, dental patients were treated with niti shape memory alloy instruments for five months, and a series of measurements showed no significant increase in the concentration of nickel ions in their blood.

Niti shape memory alloy wire bow for electrochemical immersion test and mechanical properties, and the arch wire surface electron microscopy (SEM) observation and energy disperse X-ray detection, and using inductively coupled plasma mass spectrometry (ICP - MS) was developed for the determination of the nickel ion release quantity, confirmed the niti shape memory alloy under certain mechanical stress and thermal load is the release of nickel ion is still lower than the daily dietary intake, so the niti shape memory alloy in orthopaedic stent application shows good biocompatibility.