Calcium phosphate-based biomaterials

Biomaterials and bioceramics based on calcium phosphates (CaP) have developed considerably over the last twenty years in Europe and worldwide as bone replacement materials, and have become the most widely implanted bioactive materials, particularly in orthopedic and dental surgery. These compounds have the ability to bind chemically to bone tissue and promote the formation of a stable interface at their contact; in particular, they will enable the initiation of calcium phosphate sprouting on their surface from biological fluids. In addition to calcium phosphate-based bioceramics, other bioactive ceramics are being developed for applications as bone substitutes, including those based on oxides or hydroxides, calcium carbonate, calcium sulfate or bioverres.

CaP-based bioactive ceramics were initially chosen and used because of their compositional analogy with bone mineral, and the need for a versatile material that is safe for the patient, available in large quantities and avoids the need for bone grafts.

These materials come in the form of dense or porous ceramics, coatings on metal prostheses, injectable cements, mineral-organic composites and support materials for tissue engineering. More marginally, they are used for applications other than bone replacement: for example, as ocular implants to enable eye movement, due to the property of these materials to bind to the connective tissue of the ocular cavity. Many other applications have been proposed, and some are currently under development: active ingredient vectors, nerve reconstruction guides, transfection supports. The applications of these CaP-based biomaterials discussed in this article are essentially those relating to bone and/or dental substitution.