Medical precious metals refer to the general term of gold, silver, platinum and their alloys used as biomedical materials. The precious metal has good biocompatibility, strong oxidation resistance and corrosion resistance, unique physical and chemical stability, excellent processing characteristics, and no toxic side effects on human tissue. It has been used in tooth repair, skull repair, implanted electrode electronic device, nerve repair device, ear vortex nerve stimulation device, diaphragm nerve stimulation device, optic nerve device and cardiac pacemaker electrode, etc.
Tantalum has good chemical stability and physiological corrosion resistance. Tantalum oxide is basically not absorbed and has no toxic reaction. Tantalum can be combined with other metals without destroying the oxide film on their surface. In clinic, tantalum also shows good biocompatibility. Tantalum, niobium, zirconium and titanium have very similar structures and chemical properties, and have been used in biomedical applications, such as bone plates, root implants, dentures, cardiovascular stents and artificial hearts. But in general, medical precious metals and other metals such as tantalum, niobium, zirconium are limited by their high price.
At present, titanium and titanium alloys are mainly used in plastic surgery, especially in limb bone and skull reconstruction. They are used to make various internal fixation devices for fracture, artificial joints, cranium and dura, artificial heart valves, teeth, gums, braces and crowns.
The density of titanium and titanium alloy is close to the hard tissue of human body, and their biocompatibility, corrosion resistance and fatigue resistance are better than stainless steel and cobalt alloy, is the best metal medical materials. The affinity of titanium and titanium alloy to human body stems from the ability of the compact titanium oxide (TiO2) passivation film on the surface after implantation to induce the deposition of calcium and phosphorus ions in body fluids to generate apatite, showing certain biological activity and osteobinding ability, and especially suitable for bone implantation.
