Biofilms consist of one or several microbial species and intercellular substance originating from the microbes. Biofilm structures cover many surfaces of the biosphere.

Biofilms represent the phylogenetically oldest and simultaneously still the most frequently encountered multicellular life form on earth.

Life within biofilm enables the microorganisms to reside at a location with constant supply of nutrients while being protected against shear stress, drying, UV light, pH shifts, toxic substances, bacteriophages, and last not least against all human defence mechanisms.

Once it has formed on human surfaces or within human tissues, biofilm can therefore hardly be removed neither by the activities of the immune system nor by externally applied therapeutic measures. As a consequence, pathologic biofilms are often associated with chronic infections, even more so when the biofilms form on implant materials.

The latter situation determine the period over which implant materials can reside within the human body without risking severe health problems for the respective patient.

Throughout the world there are many research groups engaged in elucidating the pathogenesis of biofilm infections. Periodontitis can be seen as a paradigm for a chronic biofilm infection with the consequences of tooth loss and systemic complications.

Even more frequently, research focuses on the modification of implant materials to generally prevent biofilm growth and on removal of biofilms once they have formed on medical devices. Such efforts are of great importance for the period over which joint prostheses can stay within a patient.