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

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