Biomaterials is a general term which is used to describe materials (synthetic or biological) which come into contact with the tissues of the human body. While a number of biomaterials are applied externally to the body, such as contact lenses or wound dressings, many are applied internally in prosthetic devices such as artificial joints or ligaments, pins for bone fixation, replacement heart valves, dental implants and medical sensors.
In the application of biomaterials in the body, consideration has not only to be given to physical properties of the material, but also to its biomechanical function and design and its biological and biochemical interactions with the living tissues. There are many good examples of the successful applications of biomaterials in prosthetic devices. Approximately half a million people in the UK have artificial joints manufactured from combinations of high strength, corrosion resistant metallic alloys and ultrahigh molecular weight polyethylene and over 50,000 patients have artificial heart valves manufactured from pyrolytic carbon ceramic. With people having ever increasing lifespans and implants being more widely used on younger patients, there are increasing demands placed on the lifetime of biomaterials in the body, with many prosthetic devices expected to last twenty years or longer. Many processes that cause failure in biomaterials and devices in the body and caused by complex interactive biomechanical and biological mechanisms. Much biomaterial research is aimed at overcoming the adverse reactions and processes that cause failure in the long-term, and the development of biologically and biomechanically active materials which can adapt to and interact positively with living tissues and cells.