Incorporation of composite bone implants in the facial skeleton

The purpose of this study was to evaluate the capacity of composite grafts consisting of either particulated cancellous or particulated cortical bone and anorganic bovine bone mineral (BBM) (Bio-Oss) to induce regeneration in standardized critical size bony defects overlying the frontal sinus. Four full thickness critical size bone defects were made in the frontal bone in each of 8 skeletally mature female goats. These defects were filled at random with composite cancellous bone/BBM grafts or composite cortical bone/BBM grafts. Control defects were not included but could be evaluated using data from a previous study in which the same experimental setting was used (Merkx et al. 1999a). Fluorochrome bone markers were injected subcutaneously 1 and 5 weeks after implantation, and 1 week before the animals were killed. Two animals were killed at 3, 6, 12 and 24 weeks after surgery respectively. The results were evaluated by histological means including fluorescence microscopy. In conclusion, composite grafts consisting of autogenous cancellous bone/BBM yield good results, combining the advantages of each material alone and reducing the disadvantages of each when used separately. Critical size defects in the maxillofacial area, overlying a paranasal sinus, filled with this material heal uneventfully within 12 weeks. Composite grafts consisting of cortical bone and BBM show less favorable results. These grafts induce osteoclasts, probably by the presence of non-functional BBM, resulting in resorption of the cortical bone chips.