An innovative biomimetic porous bioceramic to facilitate bone tissue regeneration: Microstructural characteristics, biocompatibility, and in vivo rabbit model evaluation

The present study aimed to develop a highly pure and crystalline beta-tricalcium phosphate (β-TCP) bone graft substitute using the propagated Scleractinian coral. The solid-state reaction followed by heat-treatment (1050 °C-1100 °C for 1 h) between calcium carbonate from the propagated coral and dicalcium phosphate anhydrous was performed to fabricate the coral-derived β-TCP. The microstructural, in vitro, and in vivo properties of the propagated coral and heat-treated specimens were characterized through scanning electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy, Raman spectroscopy, cell viability assay, and rabbit model. Results confirmed that the pure coral-derived β-TCP with interconnected microporosity was successfully fabricated at a temperature of 1000 °C. The co-existence of β-TCP and hydroxyapatite (HAp) was formed at the higher temperatures of 1050 °C and 1100 °C. When the temperature increased from 1000 °C to 1100 °C, the morphologies and crystalline structures in the coral-derived specimens were changed from granule-like aragonite (orthorhombic) → spherical particle-like β-TCP (rhombohedral) → tetrahedron-like (β-TCP (rhombohedral) + HAp (hexagonal)) → hexagonal-like (β-TCP (rhombohedral) + HAp (hexagonal)). Cytotoxicity assay results indicated that the coral-derived β-TCP possessed favorable biocompatibility. Moreover, histological results also demonstrated that the coral-derived β-TCP exhibited proper resorbed properties and a significantly higher percentage in new formed bone tissue than the control β-TCP specimen at 26 weeks (-p = 0.012). Thus, the coral-derived β-TCP with interconnected microporosity is a promising bone graft substitute that can be used for bone defect repair in dental and orthopedic fields.