A comparative study of the physical and mechanical properties of three natural corals based on the criteria for bone-tissue engineering scaffolds

Coral has been used for bone grafts since 1970. Because coral has the advantages of good osteoconduction, biocompatibility, and biodegradation, it is also suitable for scaffolds used in bone-tissue engineering. However, the skeletons of different species of corals often vary significantly, and very few studies focus on the assessment of the permeability and mechanical properties of coral structure. In order to better understand the use of coral in bone tissue-engineering, we selected three typical models (Acropora sp., Goniopora sp., and Porites sp.) to analyze for pore size, porosity, permeability, and mechanical strength. We found Goniopora and Porites had homogenous structure and Acropora had oriented pores and irregular pore size. Acropora had the largest permeability, however, the transverse section was closed and the useful size was limited because of its habitat type. Porites had the smallest pore size and had the lowest permeability. Our data indicated that Goniopora sp. can be considered as the most promising source of scaffolds for bone-tissue engineering because of its high porosity (73%) and that its permeability and mechanics were similar to those in human cancellous bone. In conclusion, we analyzed the impact of the macroporous structure of coral on the permeability and mechanical properties that provide indicators for designing the optimal scaffold for bone-tissue engineering.