Bioceramic

Tamura, K. et al. (2004) Effects of micro/ nano particle size on cell function and morphology, Bioceramics 26 (eds Barbosa, M.A., et al.), Trans Tech Publications, Uetikon-Zurich, pp. 919-922. 

Hench, L.L. (1991) Bioceramics from concept to clinic. Journal of the American Ceramic Society, 74, 1487-1510. 

Kamitakahara, M., Ohtsuki, C., Morihara, Y., Ogata, S. and Tanihara, M. (2005) Hydroxyapatite deposition on collagen-like polypeptide modified with silanol groups, in Archives of BioCeramics Research (eds F. Watari, T. Akazawa, M. Uo, T. Akasaka), Vol.5, pp. 210-213. 

Hench, L.L. and Andersson O. (1993) bioactive Glasses. An Introduction to Bioceramics (eds L.L. Hench and J. Wilson), World Scientific Publishing, Singapore, pp. 41. 

Bioceramics The First Weight Bearing, Completely Resorbable Synthetic Bone Replacement Materials... 

It was obvious to early researchers on synthetic bone material that a pure calcium phosphate bioceramic would be the optimum replacement for human and mammalian bone. The calcium phosphate in human bone is called hydroxyapatite (Fig. 1). It is an ionic substance having the formula Ca5(0H)(P04)3. 

HIGH-PERFORMANCE PURE CALCIUM PHOSPHATE BIOCERAMICS... 

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). 

For bone substitutes, it is very important that bioceramics have a considerable degree of porosity and particularly interconnected pores so that living bone grows rapidly into the pores. Special bone remodeling cells called osteoclasts and osteoblasts play an extremely important part of the process of rebuilding or repairing the bone. 

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. 

Megagraft 1000, the calcium phosphate bioceramic, is synthesized by chemical reaction between calcium and phosphate ion sources (6-9). This synthesis is done by taking the mixture of a calcium and a phosphate source and heating it to a temperature below the starting melting point for an extended period of time. The calcium source can be from calcium phosphates, calcium hydroxide, calcium halides,... 

Our researchers have worked very hard to accomplish our goals by doing things we felt would enhance our synthetic bone materials and their performance to enable them to equal and often exceed the performance of autograft as implants as well as in other types of bone augmentation and replacement. The nonporous tooth enamel solid calcium phosphate materials have flexural strengths of over 20,000 lb in.2 However, without pores it would take an extremely long time to resorb this nonporous bioceramic. 

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). 

Figure 9. (a) First bone grows in and fills pores in the bioceramic, (b) Under higher magnification,... 

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