In vivo evaluation of hydrothermally converted hydroxyapatite as a bone graft substitute

Eggshell (ES), mainly composed of calcium carbonate has been introduced as a possible candidate of bone substitute in reconstructive maxillofacial surgery. The purpose of this study was to evaluate the surface characteristics and bone forming ability of hydrothermally converted hydroxyapatite (HA) from hen's eggshell in vivo. ES powder was hydrothermally treated in phosphate containing solution to produce hydrothermally converted HA. Bovine bone mimerai (Bio-oss : BO), deproteinized ES, and hydrothermally treated ES in two different conditions were grafted in rat calvarial defects. The surfaces of hydrothermally treated ES showed microporous structures and the formation of HA was confirmed on EDS, XRD, and FTIR results. In animal experiment, at 4 and 8 weeks after surgery, ES grafted defects showed significantly increased amount of newly formed mineralized bone tissue compared to BO grafted defect in histomorphometric results (p < 0.05). The results of this study indicated the potential efficacy of deproteinized ES and hydrothermally converted HA from hen's eggshell as effective bone substitutes in treating osseous defects.