Bioscaffold Augmentation of the Alveolar Bone: A Pilot Study in the Rabbit to Define the Protocol

Purpose: The current study aims to establish, for the first time, a model to determine the surgical and tissue processing protocols for testing the use of a synthetic bone graft material to augment the contour and volume of the reduced alveolar ridge. Materials and Methods: β-tricalcium phosphate grafts (Vitoss®), 6mm width x 3mm height x10mm length, were placed directly onto decorticated cortical bone on the lateral aspect of the left maxillary diastema of New Zealand white rabbits (n=6). The graft was secured to the underlying bone using an 8mm x 1.4mm titanium screw, covered with a resorbable collagen membrane and the surgical site closed. Tissue blocks were harvested at 3 weeks and 6 weeks. Two non-decalcified sections were scanned using micro tomographic imaging. Four sections were embedded in resin, stained with Pyronin-G and evaluated histologically. Graft vascularisation was examined on one decalcified frozen section labelled with anti-CD31 monoclonal antibody. Results: All six sites healed well. The micro-CT analysis demonstrated maintenance of the graft height around the central screw. Histological evaluation and anit-CD31 labelling demonstrated woven bone formation and vascular and cellular infiltration within the grafted region. Quantitative analysis demonstrated increased new bone formation at the second time point (0.77 ± 0.42) compared with the first time point (0.48 ± 0.48). Conclusion: The study concluded that the model was appropriate for testing the use of a synthetic bone graft material for augmentation of a reduced alveolar ridge. The qualitative and quantitative analyses demonstrated evidence of colonisation of the graft by bone forming cells.