Evaluation of alumina toughened zirconia implants with a sintered, moderately rough surface: An experiment in the rat

Objective. Alumina toughened zirconia (ATZ) is more fracture resistant than unmodified zirconia and has been shown to be a viable substrate for the growth of osteoblasts. In this study, we examined the histological and biomechanical behavior of moderately roughened ATZ implants in rat femoral bone. Methods. Miniature implants made of ATZ with pore-building polymers sintered onto the surface and electrochemically anodized titanium (TiUnite (R)) were placed into the femurs of Sprague-Dawley rats. Implant surface topography was analyzed by 3D laserscan measurements and scanning electron microscopy (SEM). After a healing period of 14 and 28 days, respectively, histologic and biomechanical testing was performed. Results. Under the SEM, the TiUnite (R) surface could be clearly distinguished from the ATZ surface, but 3D laserscan measurements indicated a moderately rough surface topography for both, TiUnite (R) (S-a = 1.31 mu m) and ATZ (S-a = 1.51 mu m). The mean mineralized bone-to-implant contact showed the highest values after 14 and 28 days for TiUnite (R) (58%/75%) as compared to ATZ (24%/41%). The push in-values after a healing period of 14 and 28 days, respectively, increased from 20 N to 39 N for TiUnite (R) and from 10 N to 25 N for ATZ. Significance. Our findings suggest that the moderately roughened ATZ implant surface is well accepted by rat bone tissue. However, compared to titanium, the osseointegration-process of ATZ seems to proceed more slowly in that early phase of implant integration.