There are several definitions of biocompatibility. The earliest and simplest definition is that the material is not toxic to its host. This is a necessary requirement for biocompatibility, but there are additional requirements for an implanted device to perform the function for which it was designed. Consensus is moving toward Prof. David F. Williams’ definition of biocompatibility. Williams, a leading expert in biomaterials, stated, “The biocompatibility of a long-term implantable medical device refers to the ability of the device to perform its intended function, with the desired degree of incorporation in the host, without eliciting any undesirable local or systemic effects in that host.”
No foreign materials are perfectly inert. All materials will affect the host in some way. These effects may occur shortly after implantation or following a longer period of time. Williams’ definition of biocompatibility addresses this long-term impact. In addition, the application influences biocompatibility. A material may be biocompatible for an application in one area of the body, but not biocompatible for another. This difference occurs because of difference in the microenvironment in which the implant is located. It affects how the implant reacts to its environment and how the body reacts to the implant. These reactions can be highly complex, and different types of cells can react in different ways.
