In vitro interaction between tetracalcium phosphate-based cement and calvarial osteogenic cells.

Newly-developed tetracalcium phosphate-based cement (4CP cement) and cells derived from neonatal rat calvaria were cocultured to study the in vitro reaction of osteoblastic cells to the biomaterial at light and electron microscopic levels. Three-dimensional nodular structures covered with active osteoblastic cells were formed in the periphery of the test material and they contained a mineralized tissue that exhibited features closely resembling bone formed in vivo. Ultrastructurally, the test material was circumscribed with an electron-dense structure, and was immediately adjacent to elongated cyoplasmic processes with intact morphology or collagen fibrils with periodic structures. Furthermore, the mineralization of the extracellular collagenous matrix occurred directly on the surface of the material. These in vitro findings suggest the ability of 4CP cement to bind directly with newly-formed hard tissues.