By definition, biomaterials are materials from synthetic or living bodies that are used for medical purposes in order to replace a part or a function of an organ or a tissue. Several organs are thus replaced: from artificial vessels to heart valves, from hip prostheses to dental implants for example. And as it is an element to be manufactured, many materials are used to manufacture this help of humanity.
Biomaterials are usually made with metals and metal alloys such as stainless steel or titanium. This material is the most used in biomedical because it is very well known for its quality of corrosion resistance and at the same time a very good mechanical property. Orthopedic surgery uses it mainly to design dental implants or for pacemakers. But it has some disadvantages, its durability and electrochemical corrosion. It is true that this material resists corrosion, but not definitively, i.e. incompletely, and its rustproofness is not absolute. It also encounters a problem in terms of immune reactions and hypersensitivity for the recipient. The adaptation of mechanical properties is not yet resolved. Finally, friction and debris problems are also issues to be solved.
Ceramic material, i.e. alumina, zirconia, hydroxyapatite and tricalcium phosphate also find their place in biomaterials. They are used to manufacture the heads of hip prostheses, orthoses or artificial tendons in orthopaedic surgery and dental implants in the dentistry department. Hydroxyapatite, for example, is an essential element of bone, resorbing only very slowly. This synthetic material is known for its quality of being a very strong element. But it also has a handicap such as its durability, its resistance to fracture and its degradation mechanisms.
Polymeric biomaterials are widely used. The polymer is made from the combination of polymethylmetacrylate, polyhydroxyethylmethacrylate and calcium hydroxide. Its greatest asset is its quality as an osteoconductor, hydrophilic, but also osteophilic. Its function in the body is specifically to fill cavities for tumor curettage. The loss of infected substance is thus filled by this gentalline cement when it is implanted in the organism. It has a wide range of properties, from anchoring in the bone to prosthetic ligaments. But as any material resulting from human intelligence has its limits, polymeric biomaterials also have their share of drawbacks. Polymers are unstable to gamma radiation and hydrolysis. They also lack a database and a standard. Physical and chemical aging is also encountered as well as the effects of enzymes on degradation.