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 (b-TCP) bone graft substitute using the propagated Scleractinian coral. The solid-state reaction followed by heat-treatment (1050 degrees C-1100 degrees C for 1 h) between calcium carbonate from the propagated coral and dicalcium phosphate anhydrous was performed to fabricate the coralderived b-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 B-TCP with interconnected microporosity was successfully fabricated at a temperature of 1000 degrees C. The co-existence of B-TCP and hydroxyapatite (HAp) was formed at the higher temperatures of 1050 degrees C and 1100 degrees C. When the temperature increased from 1000 degrees C to 1100 degrees C, the mor-phologies and crystalline structures in the coral-derived specimens were changed from granule-like aragonite (orthorhombic)-> spherical particle-like B-TCP (rhombohedral)-> tetrahedron-like (B-TCP (rhombohedral) + HAp (hexagonal))-> hexagonal-like (B-TCP (rhombohedral) + HAp (hexagonal)). Cytotoxicity assay results indicated that the coral -derived B-TCP possessed favorable biocompatibility. Moreover, histological results also demonstrated that the coral-derived B-TCP exhibited proper resorbed properties and a significantly higher percentage in new formed bone tissue than the control B-TCP specimen at 26 weeks (*p = 0.012). Thus, the coral-derived B-TCP with interconnected microporosity is a promising bone graft substitute that can be used for bone defect repair in dental and or-thopedic fields. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).