ABSTRACT
Metals are used as biomaterials due to their excellent electrical and thermal conductivity and mechanical properties. Since the metallic bond is essentially nondirectional, the position of the metal ions can be altered without destroying the crystal structure resulting in a plastically deformable solid. Metals which are in current use as biomaterials include gold, cobalt chromium alloys, type 316 stainless steel, cp-titanium, titanium alloys, nickel–titanium alloys, and silver-tin-mercury amalgam. The first stainless steel utilized for implant fabrication was the 18-8, which is stronger and more resistant to corrosion than the vanadium steel. Stainless steels contain enough chromium to confer corrosion resistance by passivity. The noble metals are immune to corrosion and would be ideal materials if corrosion resistance were the only concern. The metallic products released from the prosthesis because of wear, corrosion, and fretting may impair organs and local tissues.
