INTERFACIAL SHEAR-STRENGTH AND HISTOLOGY OF PLASMA-SPRAYED AND SINTERED HYDROXYAPATITE IMPLANTS IN-VIVO

The interfaces of bone with sintered hydroxyapatite (SHA) and plasma s prayed hydroxyapatite-coated (HAC) implants in the femora of six dogs were examined by light microscopy, scanning electron microscopy, energ y dispersive X-ray analysis, and push-out tests. The results demonstra ted that there was no significant difference at 12 and 24 weeks after insertion between the interfacial shear strengths with bone for the tw o types of implants, however, the histological characteristics of the bone around the plasma sprayed HA could be distinguished from that of the sintered HA. The HAC implants showed an early surface biodegradati on as compared with the SHA implants. The observed differences in the interfacial zones may be attributed to different bone cell activities and variations in the dynamics of bone formation, possibly resulting f rom a higher level of dissolution/reprecipitation along the plasma spr ayed HA surface. (C) 1996 Elsevier Science Limited.