Quantitative Comparison of Osteoconduction between Porous Apatite and Wollastonite-Containing Glass-Ceramics with 5 Different Pore Sizes

Control of the porous morphology and physic- ochemical characteristics of ceramics is important for osteoconduction. In this study, we determined the influence of the porous structure of glass-ceramics that contain apatite and wollastonite (GC-AW) on osteoconduction. For this purpose, we prepared GC-AW cylinders (6 × 15mm) with 5 different pore structures (macropore size, interconnecting pore size, and presence of micropores (pore size, approximately 1µm) for each material were as follows. Material 1000G: 800µm, 150-200µm, ±; material 1000S: 800µm, 175µm, �; material 300G: 250µm, 20µm, and ++; Material 300S: 250µm, 20µm, +; and 200S: 200µm, 50-80µm, �). To evaluate osteoconduction in vivo, these materials were implanted into holes (6mm diameter) made in rabbit femoral condyles. The percentage of bone ingrowth area significantly increased in the case of 300G, 300S, and 200S at 6 and 12 weeks. At 3 weeks after implantation, the rate of bone ingrowth was faster when 1000G, 1000S, and 200S were used than when 300G and 300S were used. These results suggest that GC-AW with a pore size of 800µm is unsuitable for bone growth, and rapid osteoconduction can be achieved at interconnecting pore sizes exceeding 50µm. Further, micropores may not be important for osteoconduction in the case of highly bioactive materials such as GC-AW.