Bioceramic Materials

Bioceramic materials have developed into a very powerful driver of advanced ceramics research and development. For many years bioceramics, both bioinert materials such as alumina, zirconia and, to a limited extent titania (Lindgren et al., 2009), and bioconductive materials such as hydroxyapatite, tricalcium phosphate and calcium phosphate cements, have been used successfully in dinical practice. In addition, applications continue to emerge that use biomaterials for medical devices. An excellent account of the wide range of bioceramics available today has recently been produced by Kokubo (2008), in which issues of the significance of the structure, mechanical properties and biological interaction of biomaterials are discussed, and their clinical applications in joint replacement, bone grafts, tissue engineering, and dentistry are reviewed. The type and consequences of cellular responses to a variety of today s biomaterials have been detailed in recent books (Di Silvio, 2008 Basu et al., 2009 Planell et al., 2009). 

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We also have been able to prepare equally strong bioceramic materials of several pure calcium phosphates, which are resorbed much faster into the body as they are converted chemically to living bone by a process that we shall discuss (1-3). We have also synthesized an extremely strong (20,000-lb/in. 2 flexural strength) nonporous dental enamel material which is an excellent material for dental caps, crowns, and dentures (Fig. 3) (4). 

The secret to our success with hydroxyapatite and other strong calcium phosphates is that we seek syntheses for these bioceramics at temperatures on the order of400-800°C, where if hydroxyapatite is used as a reactant it does not decompose. Previously, most attempts failed to produce calcium phosphate bioceramic materials that were even 20% as strong as crystalline hydroxyapatite. Most crumbled under even moderate crompession in vivo. 

In Fig. 7, electron microscope photographs of two different types of high-po-rosity bioceramics are shown. The bone material on the left has 250- j. pore size with a background of micropores [Fig. 7(a)], The specimen on the right-hand side has 400- i pores with a background of 250-p pores as well as displaying micro-porosity within the pores [Fig. 7( >)]. We are also able to regulate the size and distribution of porosity in our bioceramic materials. 

Neither autograft, allograft, nor other calcium phosphate bioceramic materials of which we are aware have these properties. Figure 9(a) shows living bone with healthy bone cells (gray) deposited by osteoblasts into the pores of our bioceramic (1-3). 

Y. Huang, Porous calcium phosphate bioceramic material and its manufacture, Chinese Patent, CN1488602A, 2004. 

Calcium carbonate, mother-of-pearl, magnesite, dolomite and other inorganic materials which nature uses to provide an organism with solidity, have been categorized under the name bioceramic materials. Later some synthetic materials were added to this group. This means that the definition of a ceramic material, as given at the beginning of this book, must somewhat be adjusted as the heat treatment of a ceramic material obviously does not apply in the animal world. 

This bioceramic material is made of hydroxyapatite that has been inoculated with bone marrow stromal cells. (Mauro Fermariello/Photo Researchers, Inc.)... 

Fig. 8 A scanning electron microscope micrograph of microwave-joined MaCor and hydroxyapatite, joined at 1020°C for 20 min in a single-mode 2.45 GHz microwave cavity. (MaCor is a mica-platelet reinforced glass ceramic and HAP is a bioceramic material.) (From Ref. f Reprinted with permission of The American Ceramic Society, www. ceramics.org. Copyright 2003. All rights reserved.)...

Socio-Economic Aspects and Scope of Bioceramic Materials and Biomedical Implants... 

Willmann, G. (1995) in Bioceramics. Materials and Application, Ceramic Transactions 48 (eds G. Fishman, A. Clare, and L. Hench), The American Ceramic Society, Westerville, OH, p. 83. 

Heimann, R.B. (2010a) Bioceramic materials, in Classic and Advanced Ceramics From Fundamentals to Applications, Chapter... 

Work performed on depositing bioceramic materials, in particular, hydroxyapatite by CGDS is still few and far between. This is mainly caused by the fact that hydroxyapatite in its pure form cannot be sprayed by CGDS but requires the presence of a ductile, that is metallic matrix that provides adhesion to the substrate by deformation during impact. 

Heimann, R.B. (2002a) Modern bioceramic materials design, testing and clinical application. Engineering Mineralogy of Ceramic Materials, Proceedings of the International School Earth and Planetary Sciences,... 

Osteopontin (formerly known as bone sialoprotein I) binds tightly to hydroxyapatite in bone and thus forms an integral part of the mineralised matrix. It has been postulated to be a ligand for the vitronectin receptor, and this suggests a possible role of osteopontin in osteoclast attachment and function (Merry et al., 1993). Hence, it functions as a potent marker of ossification and consequently its expression serves to quantify the degree of mineralisation of bone tissue in contact with bioceramic materials including coatings. 

Radin SR, Ducheyne P (1992) Plasma-spraying induced changes of calcium phosphate ceramic characteristics and the effect on in vitro stability. J Mater Sci Mater in Med 3 33-42 Ramires PA, Romito A, Cosentino F, Milella E (2001) The influence of titania/hydroxylapatite composite coatings on in vitro osteoblasts behaviour. Biomaterials 22 1467-1474 Ravaglioli A, Krajewski A (1992) Bioceramics Materials, Properties, Applications. Chapman and Hall, London... 

Yoshimura HN, Gonzaga CC, Cesar PF, Miranda Jr WG. Subcritical crack growth velocities (v-K curves) of dental bioceramics. Materials Science Forum 2012 727-728 1211-1216. 

Lemons J.E., Bajpai P.K., Patka P, Bonel G., Starling L.B., Rosenstiel T., Muschler G, Kampnier S., and Timmermans T. 1988. Significance of the porosity and physical chemistry of calcium phosphate ceramics orthopaedic uses. In Bioceramics Material Characteristics Versus In Vivo Behavior. Annals of New York Academy of Sciences, Vol. 523, pp. 190-197. 

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