In vitro bone formation on a bone-like apatite layer prepared by a biomimetic process on a bioactive glass-ceramic

In this study we have investigated the behavior of fetal rat osteoblasts, c ultured up to 23 days, on a bioactive apatite-wollastonite (AW) glass-ceram ic and on the same material on which a carbonated apatite layer had been fo rmed by a biomimetic process (AWa). At the last day of culture, the specifi c activity of alkaline phosphatase activity, as determined biochemically, w as about 30% greater on AWa compared with AW disks. After the cell layers h ad been scraped off, scanning electron microscopic (SEM) observations of th e materials' surfaces revealed that mineralized bone nodules remained attac hed to both surfaces but in larger amounts on AWa. X-ray microanalysis indi cated the presence of calcium (Ca) and phosphorus (P) in the bone tissue th roughout the AWa surface and Ca, P, and silicon (Si) on the AW surface. The AW/ and AWa/bone interfaces also were analyzed after fracturing of the dis ks. The interfacial analysis showed firm bone bonding to the AW and AWa sur faces, confirmed by the X-ray microanalytic mappings. These results indicat e the importance of surface composition in supporting differentiation of os teogenic cells and the subsequent apposition of bone matrix, which allows a strong bond of the bioactive materials to the bone. Furthermore, prefabric ation of a biologic apatite layer by a method that mimics biomineralization could find application to bone-repairing materials. (C) 2000 John Wiley & Sons, Inc.