||Nishikawa T, Okamura T, Masuno K, Matsumoto H, Hirose M, Uemura N, Yasuda N, Hidaka M, Baba S, Imai K, Tanaka A
||Purpose: Coral is a porous and bioabsorptive material with physical strength that could possibly be effectively used as scaffolding for bone augmentation. To compare the characteristics of cultured and natural coral, we examined the physical characteristics and internal structure of porous corals as a scaffold material. Materials and methods: Dried blocks of cultured and natural coral (velvet finger coral) were immersed in 1N NaOH to remove protein. We then observed the exoskeleton and surface of these cultured and natural corals using micro-CT and SEM. We also measured the specific gravity, the proportion of internal cavities, and the physical strength (compressive strength, hardness) of the cultured coral when wet, and in comparison with the natural coral in the sea. Results: Cultured coral was a porous structure with tubular cavities measuring 100-250 μm in diameter and natural coral was 100-200 μm. The specific gravity and proportion of cavities, were 1.02, and 66.9%, respectively, for cultured coral, and 1.32, and 52.8%, for natural coral. The compressive strength and hardness of cultured coral were 9.3 MPa, 52.4 and those of natural coral were 26.6 MPa, 60.1, respectively. These findings suggest that cultured coral may be useful for bioabsorbable scaffold, and natural coral for bone augmentation.