Ceramic implant materials

Recently mainly synthetic materials have been used as ceramic implantation materials. Table 11.6.2 lists the most commonly used materials. 

The materials can be divided into bio-inert, bio-tolerant and bioactive materials. The difference depends on the kind of contact the tissue makes with the introduced material. 

With a bio-inert material, like aluminium oxide, the tissue makes direct contact with the implant material after some time. When a bio-tolerant material like bone cement is introduced, new bone tissue is formed at some distance from the implant. A layer of connective tissue separates the implant from the bone tissue. In the case of a bio-active material, like for instance hydroxyapaptite, new tissue penetrates the implant. In due course the original separation between the implant and tissue disappears. In this way the implant is as it were integrated into the tissue. 

There exists an inverse relationship between the biological and mechanical properties of bio-materials the better the tissue tolerates the implant material, the worse the mechanical properties of the material are (figure 11.6.3). 

The most common bio-inert materials are aluminium oxide and zirconium oxide. 

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Table 11.6.2 The most commonly used ceramic implant materials...

Greenspan DC (1999) Bioactive ceramic implant materials. Curr Opin Solid State Mater Sci 4 389-393 Gross KA (1991) Smface modification of prostheses. M Eng Science thesis. Monash University. 

Source Park, J.B., and Lakes, R.S. 1992. Ceramic Implant Materials. In Biomaterials An Introduction, 2nd ed., p. 121 Plenum Press, New York. 

Park, J.B. (1984) Biomaterials Science and Engineering, Plenum, New York. A textbook covering all aspects of biomaterials. The section covering ceramic implant materials is quite brief, but there is information about polymers and metals and a general background about the field. 

FIGURE 38.2 fxCX representation of a highly porous biphasic ceramic implant material (Camceram , Cam Implants, Leiden, The Netherlands) with a HA TCP ratio of 60 40, porosity of 90%, and macropores ranging from 300 to 500 (xm. Bar represents 1 mm. 

Over time a large variety of materials have been used, including ivory, stainless steel, chromium—cobalt, and ceramics for the acetabular component. None proved sufficient. The implant material composition must provide a smooth surface for joint articulation, withstand hip joint stresses from normal loads, and the substance must disperse stress evenly to the cement and surrounding bone. 

Other Ceramic Calcium Phosphate Materials. Other ceramic calcium phosphate materials for repairing bony defect iaclude p-tricalcium phosphate (P-TCP) [7758-87-4], P-Ca2(PO, and biphasic calcium phosphate (BCP) ceramics which consist of both P-TCP and HA. Unlike ceramic HA, P-TCP resorbs ia the tissue (293). The in vivo dissolution of BCP ceramic implants was shown (296) to iacrease with increasing P-TCP/HA ratio ia the implants. Both P-TCP and BCP can lead to new bone growth to various extents depending on the appHcations and the type of materials used (293,296). 

Thomas J. Webster, Nanophase Ceramics The Future Orthopedic and Dental Implant Material Yu-Ming Lin, Mildred S. Dresselhaus, and Jackie Y. Ying, Fabrication, Structure, and Transport Properties if Nanowires... 

The concept of microfabrication on powder surfaces can be used in many industrial fields, e.g., in pigments, printing inks, paints, foods, pharmaceuticals, detergents, cosmetics, dental materials, implant materials, copy toners, ceramics, cements, electrorheological materials, and metallurgy, etc. (I). 

There are countless applications possible. Nowadays, it is possible to replace human parts with synthetic materials virtually anywhere in the body. Table 11.6.1 lists a number of examples of plastic and metal implants. Ceramic implants are not mentioned here because they will be discussed elaborately in this chapter. 

In 1993 Rock patented the use of aluminium oxide ceramics as implant materials Patent-erteiling liber Aluminiumoxidekeramik fur das Innere und AuBere des menschlichen und tierischen Korpers . 

NANOPHASE CERAMICS THE FUTURE ORTHOPEDIC AND DENTAL IMPLANT MATERIAL... 

Orthopedic and dental implant materials bioceramics, 145-146 chemical modifications, 147-148 comparing mechanical properties of, and bone, 146 conventional, 127 costs, 126-127 current materials, 145-148 fate of implanted device, 140-141 integration into surrounding tissue, 127 integrin expression on osteoblasts, 144 integrins, 143-144 metals, ceramics, and polymers, 145 next generation, 127,148-159... 

The chapters in this volume present detailed insights into the synthesis-structure-properties relationships of nanostructured materials. In particular, the catalytic and photocatalytic properties of nanoclusters and nanostructured materials with ultrahigh surface-to-volume ratio are demonstrated. The gas absorption characteristics and surface reactivity of nanoporous and nanocrystalline materials are shown for various separation and reaction processes. In addition, the structural manipulation, quantum confinement effects, transport properties, and modeling of nanocrystals and nanowires are described. The biological functionality and bioactivity of nanostructured ceramic implants are also discussed. 

This brief description of processes in bone indicates that it is chemically very active. For this reason, the objective of research in bioceramic is to mimic the internal processes and the structure of bone with man-made materials. Once placed, there should be little distinction between the natural bone and man-made ceramic implant or an artificial graft. 

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