Three-dimensional bone response to commercially pure titanium, hydroxyapatite, and calcium-ion-mixing titanium in rabbits

Three-dimensional bone response to 3 biomaterials--commercially pure titanium (Ti), hydroxyapatite (HA), and calcium-ion-mixing titanium (Ca-Ti)--embedded in the tibiae of rabbits was examined chronologically. The rabbits were sacrificed at 2, 4, and 8 weeks after implantation, and the percent bone volume around each implant was calculated from the implant surface to each of 4 measurements: 36 microns, 0.25 mm, 0.5 mm, and 1.0 mm in 2 regions (cortical bone and bone marrow regions). Percent bone volume in the cortical bone was consistent, whereas in the bone marrow region, the percent bone volume varied according to implant material, implantation period, and distance from the implant surface. With Ti implants the percent increased gradually up to 8 weeks at each distance, whereas in HA and Ca-Ti implants the percent was largest at 4 weeks and increased closer to the surface. The percent with Ti implants was largest at 36 microns to 0.25 mm. Aspect of bone response to Ca-Ti was its position intermediate between those of HA and Ti. The decrease of the percent at 8 weeks was smaller than HA.