Porous Ca-P-O bio-glassceramics by loose-powder-sintering
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Porous Ca – P – O bio-glassceramics by loose-powder-sintering T. S. China) Department of Materials Science and Engineering, Tsing Hua University, Hsinchu, 300, Taiwan, Republic of China
D. C. Wu and M. P. Hung Department of Materials Engineering, Cheng Kung University, Tainan, 701, Taiwan, Republic of China
C. P. Wang Department of Biology, Cheng Kung University, Tainan, 701, Taiwan, Republic of China (Received 6 June 1994; accepted 8 December 1995)
Porous resorbable Ca –P–O glassceramic tooth roots based on calcium biphosphate were prepared by loose-powder-sintering then crystallization-annealing. The glass composition is, by weight, CaOy(CaO 1 P2 O5 ) 0.33. The sintering behavior of the glass can be described by a conventional viscous flow model. The resultant glassceramic has a pore size of 6 to 36 mm, depending on starting particle size and sintering temperature, while the pore size distribution is independent of sintering time. The flexural strength is 33 to 150 MPa depending mostly on crystallization-annealing treatment. The crystalline phases are b –Ca2 P2 O7 and CaP2 O6 . After being implanted into rabbits, these porous implants show remarkable biocompatibility and induce the ingrowth of new bone within 30 days. They are partly resorbed after 90 days and replaced by new bone. In spite of the original small porosity, the ingrowth of blood vessels and bone cells is abundantly seen after 90 days, due to enlarged pores produced by progressive resorption. This glassceramic is a good candidate for resorbable tooth and bone implants. The loose-powder-sintering technique resulting in intricate bulk shapes with controllable pore size distribution and good machinability as well as adjustable mechanical strength hence is a powerful technique for the preparation of porous glassceramics.
I. INTRODUCTION
Bioceramics, including glassceramics, are categorized into bioinertness, e.g., alumina, bioactiveness, e.g., hydroxylapatite, and biodegradability, e.g., calcium aluminate and tricalcium phosphate.1–3 Some of them can be readily machinable to enhance implantation operations.4 They are widely used as prosthetic or artificial internal organ materials of physiological functions.1–4 Porous compacts, metallic or ceramic, are widely used as bioimplants. In these bioimplants, the tissueimplant bonding strength and the ingrowth of tissue are essential.1–3,5,6 Porous bioceramic implants facilitate the ingrowth of tissue and hence the bonding strength. For the inert porous implants with pore size of 100 mm or larger, the growth of bone structure, new blood vessels, and Harversian systems in the pores can be observed with an optical microscope. There is mineralization while no infectious nor abnormal cell growth at the interface.7 For resorbable or biodegradable porous
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J. Mater. Res., Vol. 11, No. 4, Apr 1996
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implants, the pore size is much smaller than in the case of ine
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