Biocompatibility

As biocompatible ( gr bios = life compatible = compatible ) refers to materials or assemblies that have no negative impact on living organisms in their environment.

Particularly relevant is the biocompatibility of implant, since they are for a long period of time in direct contact with an animal. The certification of biocompatibility of medical materials and products in accordance with ISO 10993 1-20. To achieve a high biocompatibility, the implants can of a non- biocompatible material with a biocompatible layer, for example from proteins, may be coated. This is then called surface compatibility. If the implant in the form and internal structure adapted (for example, fiber strength ) to the recipient tissue, it is called structural biocompatibility.

To test the biocompatibility of various biological substances and implants in laboratory tests on their compatibility in the human and in the animal body to be examined. This lengthy series of tests are part of the world stringent approvals for implants and drugs.

Subdivision of biocompatibility

If it can not be described as incompatible material, the subdivision of the biocompatibility involves three terms biotolerant, bio-inert and bioactive.

Biotolerant

The products which are referred to as " biotolerant " allow a residence time of the medical device in the body of months up to several years. Occur minor flaws in the tissue reaction. This species is not bioactive and not long-term " bio-inert ". In the long term, the term is meant that there is no decomposition, no cell change, and no toxic effects in the period of use (in-vivo ).

Bio-inert

The term " bio-inert " includes in fact, that there is no chemical and / or biological interaction between the implant and the tissue. No release of toxic substances. Quite However, this is to never reach as more occurs an interaction between tissue and implant. However, if this interaction is sufficiently low, so that at no time entered in the body substances exceed certain limits, it is called a bio-inert material. The body responds to this material usually with a non-adherent ( overgrown ) Bindegewebskapselung around the implant, and there is no rejection of the body instead. This connection can only transmit compressive forces, as the layer of connective tissue, causing a sliding of the implant under stress with tensile forces. The term " bioinert " requires corrosion resistance. The material should be thermally stable (e.g., for sterilization ), refractory (non- responsive ) and passivated (e.g. for coating ) to be allocated as a material, the term " bio-inert ". This class includes some ceramics (such as Al2O3), plastics and most metals.

Bioactive

In arthroplasty refers to "bioactive " in the reaction of bone to the implant, which permits adhesion of the bone at the interface to the implant. This can be achieved by a coating. Thus, a bioinert material eg respond by coating " bioactive". The implant material, but usually only the coating is converted into bone. This chemical compound is cohesively and leaves compared to bio-inert materials to transfer tensile loads to. For other medical applications, it refers to the active efforts of the body, the implant the required tasks (such as heart valves, pacemakers ) in the long term ( see above) can take over and thus produce the complete replacement. Typical materials which are " bioactive" counted mostly on the concept, consisting of carbons, ceramics and glasses ( for example, Bioglass ®).

Biocompatibility in waste management

Wherein waste water is a measure of the biocompatibility, the biodegradability of the polluting substances. It is calculated from the quotient of the biological oxygen demand (BOD ) and chemical oxygen demand ( COD ). Solids is the time which is necessary for the biological-chemical decomposition, a suitable measure to describe the biocompatibility.