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Osteoconduction on, and Bonding to, Calcium Phosphate Ceramic Implants
Published online by Cambridge University Press: 15 February 2011
Abstract
Calcium phosphate ceramic blocks of three different densities, porous, intermediate and dense, were prepared by tape casting (total = 18), and implanted in the femora of 9 Wistar rats for 1 to 3 weeks. Following fixation, the tissue was prepared for examination by scanning electron microscopy (SEM) of freeze fractured specimens, or back-scattered electron imaging (BSEI) of polymethylmethacrylate (PMMA) embedded, undecalcified, sections. The results demonstrated that while all ceramics were osteoconductive, the 93 % dense implants showed no evidence of bone bonding as judged by the plane at which specimens separated or cracked during preparation for microscopy. The porous ceramics, on whose surfaces both multinucleated cells and osteoid tissue were observed at all implantation times, exhibited less bone contact than the other two groups. Both SEM and BSEI showed that there was bone growth into the microporosity of both intermediate and porous ceramics, pore size range 1−2μ m, to a depth of about 6μm. The latter corresponds to the thickness of natural bone lamellae. In all implants examined, de novo bone formed on the ceramic surface by the initial production of a biological cement-line like interfacial extracellular matrix. The results clearly show that osteoconduction and bone-bonding are distinct mechanistic phenomena. While we assume the former to be a consequence of protein adsorption events culminating in anchorage of osteoblasts to the implant surface, the latter is the result of mechanical interdigitation of the extracellular matrix, produced by osteoblasts, with the microtopography of the implant surface.
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- Copyright © Materials Research Society 1996
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