Biocompatibility means the compatibility of artificial materials in direct contact with the human organism and the resistance of materials in the biological environment. These material properties are particularly important for implant dentistry. Lack of biocompatibility can provoke implant rejection.
What is biocompatibility?
Biocompatibility means the compatibility of artificial materials in direct contact with the human organism, e.g., dental implants. In implantology, artificial materials are introduced permanently into a person’s body or are intended to remain in the organism for at least a certain period of time. In connection with the materials used, the concept of biocompatibility plays an important role. The implanted materials must neither have a negative influence on the tissue or the organism, nor cause damage in the organic environment itself. Even apart from implantology, biocompatibility can be relevant. This is basically the case whenever certain materials are in direct contact with people and their environment over a certain period of time. Medical materials and products are labeled with the property of biocompatibility according to ISO 10993 1-20. To achieve the highest possible biocompatibility, implants made of non-biocompatible materials are coated with biocompatible coatings, for example. Proteins are most frequently used to ensure surface compatibility. Structural biocompatibility, on the other hand, is when the internal structure of the implant has been adapted to the structure of the target tissue. Biocompatibility is ensured in laboratory tests in which medical materials are tested for their compatibility in the human and animal body. The series of tests for this are lengthy and are considered a requirement for approval of implants and drugs worldwide.
Function and task
Implants, meanwhile, can support or even replace bodily functions. They can equally well have aesthetic benefits and thus contribute to the mental health of patients. In implant dentistry, the biocompatibility of implants benefits patients in that the risk of rejection or poisoning is kept as low as possible through materials testing. In the context of medications, ensuring biocompatibility also prevents symptoms of poisoning or other incompatibilities. If a material or material cannot be classified as compatible in compatibility testing, it is biotolerant, bioinert or bioactive. Biotolerant products can remain in the human body for several months or even years without causing serious damage. In some cases, minor deficiencies occur in the tissue reaction. After positive testing, in addition to decomposition, cellular alteration and toxic effects are excluded during the period of use tested. Bioinert products do not cause chemical or biological interactions with tissues. Toxic substances are hardly released into tissues by these materials. The interaction between the material and the body is sufficiently low and only a few substances pass into the body. Biocompatible materials are enclosed in non-adherent connective tissue capsules, do not cause a rejection reaction and react to the biological environment in a corrosion-resistant manner. The material is usually thermally stable, refractory and passivatable. Medical ceramics, plastics and metals in particular fall into this biocompatibility group. Bioactive materials play a role especially for endoprosthetics. Endoprosthetics describes the reaction of a bone to the implant as bioactive if adhesion of the bone to the implant boundary is possible. Materials become bioactive through coating. In most cases, a bioinert material is made bioactive by further processing. The implant material of bioactive materials becomes bone material. In other cases, the term bioactivity is used to describe the active effort of the body to give the implant a specific function in the long term. Carbons, ceramics and bioglass products are typical materials with bioactivity. Biocompatibility can also play a role in waste management. In the case of wastewater, for example, biocompatibility is a measure of the biodegradability of contaminating substances.
Diseases and ailments
The biocompatibility of implants is of paramount relevance in the context of various diseases. For example, various cardiac conditions may require the use of an implantable cardioverter-defibrillator or pacemaker. Implants and biocompatibility may be equally relevant in the context of vascular diseases, as they may require stents or vascular prostheses. In eye disease, retinal implants serve as visual prostheses. In dentistry, dental implants are used as fixation for artificial teeth. Other implants serve as depots for a specific drug. For many of these implants, biocompatibility in the sense of bioactivity determines the extent to which the intervention will be useful in relieving the patient’s symptoms. A truly bioactive artificial heart valve, for example, is fully accepted by the body. The organism thus actively assigns to the implant the tasks that the heart itself cannot perform due to the heart disease. If the bioactivity of the implant is too low, such active transfer of functions by the patient’s organism does not occur. The implant is rejected and the therapy path shows no success. Rejection of artificial implants due to low bioactivity can sometimes be life-threatening, depending on the shape of the implant. In other cases, medical materials cause poisoning or systematic immunological inflammation due to insufficient biocompatibility. Such a correlation is virtually eliminated in modern medicine today due to rigorous testing for biocompatibility.
