Bone formation with nano-hydroxyapatite from eggshell

Hydroxyapatite, (Ca₁₀(PO₄)₆(OH)₂ is chemically similar to the mineral component of bones and teeth. HAp is among of the few materials that are classified as bioactive, meaning that it will support bone ingrowth and osseointegration when used in orthopaedic, dental and maxillofacial applications. Hydroxyapatite may be employed in forms such as powders, porous blocks and hybrid composites to fill bone defects or voids. These may arise when large sections of bone have had to be removed or when bone augmentations are required (e.g. dental applications). In this work, nanohydroxyapatite (nano-HAp) was successfully produced by using recycled eggshell and phosphoric acid by mechanochemical activation method (e.g. attrition milling). Nano-HAp bioactivity was evaluated in animal (rabbit) models. Sixteen 4-month-old New Zealand white rabbits with an average weight of 2.8kg were used in experiments. After bilateral parietal bony defects formation (diameter: 8.0mm), nano-HAp was grafted. The control was unfilled defect. The bone regeneration was evaluated by micro-computerized tomograms (μCT) and histomorphometric analysis at 4 and 8 weeks. In conclusion, nano-HAp from eggshell showed much more bone formation compared to unfilled control group in both μCT analysis and histomorphometric analysis. Considering that the eggshell is easily available and cheap, nano-HAp from the eggshell can be good calcium source in tissue engineering.