SEM‐EPMA observation of three types of apatite‐containing glass‐ceramics implanted in bone: The variance of a Ca‐P‐rich layer

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Abstract
The progressive changes of a Ca-P-rich layer between bone and three types of apatite-containing glass-ceramics of the same chemical composition: MgO 4.6, CaO 44.9, SiO2 34.2, P2O5 16.3, CaF2 0.5 (in weight ratio) were examined. Plates (15 mm × 10 mm × 2 mm, mirror surface) containing apatite (35 wt%) (designated A-GC), apatite (35 wt%) and wollastonite (40 wt%) (designated A · W-GC), and apatite (20 wt%), wollastonite (55 wt%), and whitlockite (15 wt%) (designated A · W · CP-GC) were prepared. They were implanted into the tibia of mature male rabbits for 5 days, 10 days, 20 days, 30 days, 60 days, 6 months, and 12 months. All three types of glass-ceramics showed direct bonding to the bone 30 days after implantation. It was observed by SEM-EPMA 30 days after implantation that Si and Mg content decreased, P content increased, and Ca content did not change across the reactive zone from the glass-ceramics to bone. The level of P and Si in the A · W · CP-GC changed five days after implantation. In A · W-GC and A-GC, a little change in P and Si levels was observed between 10 and 20 days after implantation. The width of reactive zone was narrowest with A-GC, wider with A · W-GC, and widest with A · W · CP-GC. The dissolution of glass-ceramics stopped 6 months after implantation. This phenomenon shows that the glass-ceramics may be suitable for clinical use.