Ceramics synthetic bone substitutes

Although Plaster of Paris was used inl892asabone substitute [Peltier, 1961], the concept of using synthetic resorbable ceramics as bone substitutes was introduced in 1969 [Hentrich et al., 1969 Graves et al., 1972]. Resorbable ceramics, as the name implies, degrade upon implantation in the host. The resorbed material is replaced by endogenous tissues. The rate of degradation varies from material to material. Almost all bioresorbable ceramics except Biocoral and Plaster of Paris (calcium sulfate dihydrate) are variations of calcium phosphate (Table 39.8). Examples of resorbable ceramics are aluminum calcium phosphate, coralline. Plaster of Paris, hydroxyapatite, and tricalcium phosphate (Table 39.8). 

A few million patients every year need a bone graft or bone graft substitute to repair a bone defect resulting from an injury or a disease. A large number of bone graft substitutes can be used unprocessed or processed allogenic bone, animal-derived bone substitutes and synthetic bone substitutes, mostly ceramics. ... 

Hydroxyapatite (HAp) [Caj (PO )g(OH2)] is the main inorganic mineral constituent close to human bone chemistry, and is also an outstanding synthetic bone substitute because of its osteoconductive properties. HAp ceramics can be manufactured synthetically from its constituents via a range of production methods. In addition, they have been manufactured by demineralizing bovine or human hard tissues. 

Natural bone is made of 60% of inorganic calcium phosphate minerals. " To this end, many researchers have developed synthetic bone substitutes based upon ceramics to better mimic the natural composition of bone. Ceramics have been widely used for orthopedic and dental applications, and have been used... 

Yamasaki, N., Hirao, M., Nanno, K., Sugiyasu, K., Tamai, N., Hashimoto, N., Yoshikawa, H., and Myoui, A. 2009. A comparative assessment of synthetic ceramic bone substitutes with different composition and microstructure in rabbit femoral condyle model. Journal of Biomedical Materials Research Part B Applied Biomaterials 91 788-98. 

Hydroxyapatite is a bioactive ceramic that is commonly used in particulate form in bone repairs, as well as coatings for metaUic prostheses to improve their in vivo biological response. Due to the chemical similarity between HA and mineralized bone, synthetic HA exhibits a strong affinity to host hard tissues. The formation of chemical bonds with the host tissue offers HA a greater advantage in cUnical applications over other bone substitutes such as allografts or xenografts. 

Several synthetic materials for bone substitution have been developed and characterized during the last few decades. Different approaches have been used for the design of bone substitute materials. Most are formulated as granules of different sizes or porous blocks (or sponges). The aim of this section is to provide an overview of the currently available ceramic bone substitutes. 

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