Interface between bone and nacre implants in sheep.

We have investigated the interface between bone and chronic implants of nacre in sheep. There was no foreign body reaction over the period of 10 months and the implants were not broken down. Light microscopy indicated activity within an osteoprogenitor cellular layer lining the implant, resulting in a complete sequence of new bone formation. Nacre appeared to bind directly to newly formed bone without any intervening fibrous tissue. Scanning electron microscopy and energy dispersive photon X-microanalysis showed calcium and phosphate ions lining the nacre within the osteoprogenitor tissue. These studies show a dynamic activity of the bone/nacre interface, leading to continuity between the nacre and the bone.