Hydroxyapatite Nanoparticles as Injectable Bone Substitute Material in a Vertical Bone Augmentation Model

Aim: The aim of this in vivo study was to evaluate the utility of bone graft gel containing hydroxyapatite nanoparticles in promoting bone regeneration in a mouse model of vertical bone augmentation. Materials and Methods: Gel implants with high and low viscosity were compared for their bone regenerating ability. Bone formation at 12 weeks and material reactions were observed radiographically and histologically. Results: Radiological analysis showed that most bone augmentation area in the graft material occurred in the fourth week after surgery regardless of the viscosity of the gel, and then gradually decreased. The volume of bone augmentation area was greater in the high-viscosity implant group than in the low-viscosity implant group at all time points, the difference was statistically significant at 8 and 12 weeks. Histological evaluation indicated that the new bone area was significantly smaller in the high-viscosity implant group. Conclusion: Gelatinous graft materials containing hydroxyapatite nanoparticles were confirmed to be useful in vertical bone augmentation.