First histological observations on the incorporation of a novel calcium phosphate bone substitute material in human cancellous bone

Calcium phosphates are frequently used as bone substitute materials because of their similarity to the mineral phase of bone, absence of antigenicity, and excellent osteoconductivity. However, in most currently available mine ral substitutes, resorption occurs slowly if at all. In contrast, calcium p hosphate cements have shown rapid resorption and remodeling in animal studi es. In two prospective studies, a novel amorphous calcium phosphate cement (Biobon(R)) was implanted in human patients for the first time. After 2-12 months, ten biopsies were obtained from nine individuals during secondary s urgical interventions, for example, for implant removal. In all specimens, partial replacement of the material by new bone was observed, while residue s of the cement were still visible. Undecalcified sections revealed extensi ve bone formation in immediate contact to the cement without fibrous interf ace. Polynucleated cells and superficial lacunae were indicative of resorpt ive activity, but inflammatory tissue response was absent. The new bone dis played regular trabecular and osteonal patterns. The histologic findings ar e in accordance with the excellent biocompatibility observed in the clinica l follow-up. Though still incomplete, the resorbability of this cement appe ars superior to sintered calcium phosphates in these biopsy specimens. Pres umably this is due to its amorphous crystalline structure. Biobon(R) merits further studies as a promising substance for bone defect reconstruction in non-stress-bearing areas. (C) 2001 John Wiley & Sons, Inc.