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Biomaterials for implant and joint replacements

Virtually everyone has a biomaterial in his or her body. These can range from the common tooth filling to more critical implants like joint replacements and cardiovascular implants. These have served us well in the past, however, as life expectancies increase, and as operations become more complex, a new range of biomaterials is being developed which will last longer and adapt better to the human body.
Biomaterials for implant and joint replacements
A group of Russian researchers have developed a range of bioceramic and composite materials, which can be used in a variety of medical applications. These bioceramic materials contain hydroxyapatite as the bioactive component. Hydroxyapatite is chemically similar to the mineral component of bone and as such is one of the few materials that can be classified as bioactive, meaning that it will support bone growth. It is quickly integrated into the human body without fear of rejection, and it will bond to bone forming strong, indistinguishable unions. As such it can be used in orthopaedic and dental applications.

Specifically, a biocompatible oxide coating for titanium implants, bioceramic materials for bone replacement and stomatological porcelain have been developed. Titanium is used in dental and orthopaedic applications since it is inert and does not have any adverse interactions inside the body. However, the body can recognise such implants as foreign as it tries to isolate them by encasing them with fibrous tissue. This new research involves coating the implants with a bioactive material, which does not interact with the tissue around it. It contains a bioactive osteoconducive calcium-phosphate coating, which ensures bone growth on its surface. This can be used as a coating in many titanium based applications, for example knee and hip replacement prosthesis.

A bioceramic material containing hydroxyapatite has also been developed for building up bones and filling holes in degraded bones, in cases where large sections of bone have been removed, for example in bone cancers. The essential feature of the material is the necessary porosity and strength that provide the intergrowth of bone tissue to the artificial implant pores. The material has a porosity of 45-60%, bioactivity of 70-90%, a bending strength of 20-50MPa and compression strength of 80-150MPa. The material encourages the rapid filling of holes by naturally forming bone and becoming part of the bone structure. This also eliminates the need for bone grafts.

The material can be used in stomatologial porcelain to create a multi-layer ceramic coating on metallic crowns. The coating is characterised by high durability, a good aesthetic effect and biological inertness. The use of these bioceramic materials will provide the basis for substantially improved surgical procedures.
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