Comparative Study of hydroxyapatite prepared from seashells and eggshells as a bone graft material

The aims of this study were to determine the physical properties of hydroxyapatite from seashells (sHA) and from eggshells (eHA), to analyze elements within sHA and eHA, and to compare the bone regeneration ability between sHA and eHA in a rat parietal bone defect model. The sHA and eHA particles had a similar morphology in scanning electron microscope images. From the Fourier-transform infrared absorbance spectra and X-ray diffraction results, both types of hydroxyapatite (HA) had the characteristics of pure HA. Inductively coupled plasma atomic emission spectroscopy results suggested that the sHA had higher levels of sodium and strontium than the eHA, whereas the eHA had higher levels of magnesium than the sHA. In μ-CT results, the mean bone mineral density of the sHA was significantly higher than the control at 4 weeks after the operation (p = 0.012). The mean bone volume of the eHA was significantly higher than the control at 8 weeks after the operation (p = 0.012). In the histological images at 4 weeks after the operation, foreign body multinucleated giant cells were observed around the agglomerated sHA particles, while there were fewer inflammatory reactions around the agglomerated eHA particles. The eHA group showed better results in bone formation than did the sHA group in this study.