Coralline hydroxyapatite bone graft substitute: A review of experimental studies and biomedical applications

A review of the various coral bone graft substitutes currently available for experimental and biomedical applications and ongoing investigations of coral derived bone replacement materials is presented here. Natural and synthetic graft materials that have been studied in vitro and in vivo and used in different medical procedures in osseous tissue have focused mainly on freeze-dried bone, hydroxyapatite (HA), tricalcium phosphate (TCP) and coral. Coralline hydroxyapatite (CHA) is manufactured from marine coral, which has a natural trabecular structure similar to that of bone, by the hydrothermal conversion of the calcium carbonate skeleton of coral to hydroxyapatite, a calcium phosphate. While many studies have demonstrated promising biocompatible properties and osteogenic results, as a bone graft substitute and bone void filler, the use of CHA may be limited owing to its inherent mechanical weakness and reduced biodegradation. The benefits of CHA as bone graft are predominantly its safety, biocompatibility and osteoconductivity so that it can be used as a substitution biomaterial for bone in many indications clinically. CHA can also be used as an efficient carrier system for the local delivery of growth factors to enhance osteointegration and implant fixation into peri-implant osseous tissue.