Nano Biomedicine
Bone-regeneration Trial of Rat Critical-size Calvarial Defects using Nano-apatite/collagen Composites

Wataru HATAKEYAMA1, Masayuki TAIRA2, Kyoko TAKAFUJI1, Hidemichi KIHARA1, and Hisatomo KONDO1

1Department of Prosthodontics and Oral Implantology, Iwate Medical University School of Dentistry, Moriaoka, Japan
2Department of Biomedical Engineering, Iwate Medical University, Iwate, Japan

Nano Biomedicine 2013;5(2): 95-103, (Dec 30)

Dentistry needs new bone substitute materials. The purpose of this study was to prepare nano-hydroxyapatite/collagen composite (n-HAP/Col); and evaluate its usefulness as osteo-conductive bio-material by using animal model. We formed collagen control (Col) and n-HAP/Col specimens of 6 mm width and 1 mm height, by freeze-drying, de-hydrothermal cross-linking and punching. Critical-size bone defects (6 mm) were generated in the cranial bones of thirty-six 10-week-old Wistar rats, in which Col and n-HAP/Col specimens were implanted. After feeding for 1 day, 4 weeks, or 8 weeks, the rats were sacrificed (n=6). Micro-computed tomography (CT) revealed that at 4 and 8 weeks the defect zones implanted with Col had similar mean opacity values of around 105, compared to that of 70 after 1 day (p<0.05); whereas at 4 weeks those implanted with n-HAP /Col had a much larger mean opacity value of 149, compared to those of 109 at 1 day (p<0.05) and 123 at 8 weeks. Histological observations of the rat cranial defect zones implanted with n-HAP/Col for 8 weeks revealed that n-HAP/Col was completely eliminated, and new bone was partially formed. Taken together, it was considered that n-HAP/Col was osteo-conductive, most effective at 4 weeks while newly formed bone slightly decreased at 8 weeks. Withal limited experimental results, it can be concluded that n-HAP/Col could be used as new osteo-conductive bone substitute material. For better osteo-regeneration at cranial defects over 4 weeks, it was recommended to add growth factors and stem cells to n-HAP/Col in future studies.

Key words: nano-apatite, collagen composite, bone re-generation, micro-CT, histological observation

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