Reconstruction of the mandible by prefabricated autogenous bone grafts. An experimental study in minipigs.

The aim of the present experimental study was to evaluate the use of prefabricated bone grafts for reconstruction of the mandible. In 20 adult Göttingen minipigs, prefabricated bone grafts 10 x 12 x 40 mm in size were cultivated in scaffolds of pyrolized bovine bone under a polylactic membrane on the outside of the mandible during a period of five months. The grafts were harvested and transferred to bridge 2- and 4-cm lower mandibular border defects and discontinuity defects. Five animals served as ungrafted controls and evaluation of the grafts was performed three and five months after grafting. At both intervals and in both graft-length groups, the grafted bone volume was almost completely preserved inside the scaffolds and exhibited a slight (3 months) to marked (5 months) increase in bone density by appositional bone growth. The inserted screws were histologically integrated into the transplanted bone and the grafts were linked to the adjacent mandibular bone without intervening soft tissue. The grafts, which were transferred to bridge discontinuity defects, were likewise well preserved with direct fusion between the grafted bone and local bone. It was concluded that bone grafts can be prefabricated from underlying mandibular bone and used for the repair of mandibular defects of various length and shape.