Bone bonding behavior of the hydroxyapatite containing glass-titanium composite prepared by the Cullet method

Bioactive composites composed of hydroxyapatite containing glass (HA-G) as a coating and titanium (Ti) or titanium alloy implants as a substrate were prepared by the Cullet method. This method results in the HA-G coating laye r on the substrate with a compositional gradient in HA concentration. The r esults of in vitro and in vivo experiments investigating the characteristic s of the composite materials are reported and discussed in this article. In vitro evaluations confirmed that the Cullet method was suitable for the pr eparation of the functionally gradient composite implants with higher relia ble quality. In vivo experiments permitted evaluation of bonding strength o f these composite implants to living bone tissue. Mechanical pull-out tests indicated that the implants bonded to living bone at least as firmly as th ose by the conventional method, and that the adhesion between the HA-G coat ing layer and metal substrate was well integrated and strongly maintained i n vivo. SEM observations with EDX and a histological study of the interface between the HA-G-Ti composite implants and bone tissue revealed not only t hat the implants bonded to bone directly without any intervening tissue but that bone ingrowth into the HA-G layer occurred. The HA-G-Ti composite imp lants demonstrate both biocompatible and osteoconductive characteristics, a nd may be expected to obtain good and lasting results when applied clinical ly. (C) 2001 Elsevier Science Ltd. All rights reserved.