HISTOMORPHOMETRICAL AND MECHANICAL EVALUATION OF TITANIUM PLASMA-SPRAY-COATED IMPLANTS PLACED IN THE CORTICAL BONE OF GOATS

The aim of this study was to investigate the biological and mechanical response of bone to titanium plasma-sprayed implants of different rou ghnesses. Three types of titanium plasma-spray coating were applied to beam-shaped implants: Ti2, Ti3, and Ti4, with a Ra of 16.5, 21.4, and 37.9 mu m, respectively. An Al2O3 grit-blasted implant (Ti-un) with a Ra of 4.7 mu was used as a control. In total, 72 implants were insert ed in the tibial cortical bone of nine adult female goats. These impla nts were evaluated histologically and mechanically 3 months after impl antation. At the end of the experiment, of the 72 inserted implants, t wo implants tone Ti2 and one Ti4) were lost. Histological evaluation o f the other retrieved implants revealed a uniform bone reaction for al l implants. The unloaded plasma-spray coatings showed no signs of dela mination at the implantcoating interface. Occasionally, particles of t he Ti4 coating broke free and were found near the implant. Histomorpho metry revealed no difference in bone contact for the different implant s (P > 0.05). Furthermore, the push-out test showed no significant dif ference (P > 0.05). Linear regression showed no interaction between th e push-out values and the roughness values (r = 0.5). On the basis of these results, it may be concluded that the used surface roughnesses d id not lead to differences in bone response or mechanical attachment s trength in goat cortical bone. (C) 1998 John Wiley & Sons, Inc.