Various materials are implanted within the human body as a result of of medical need. Dental implants, stabilizing plates, arterial stents, and orthopedic replacements are all common examples where a material is implanted within the body.
The typical response of the immune system to any foreign body is to attack the implant. If the immune system cannot eradicate the foreign body, then it attempts to encapsulate it instead. This self-preserving attack from the immune system can lead to implant failure, and the likelihood of failure is, in part, dependent upon the bio-reactivity of the material. For example, stainless steel has been evaluated to be less reactive than more base steel alloys, and titanium has been found to be less reactive than stainless steel.
How is bio-reactivity characterized, and how is it measured over the conditions of a long term implantation?