Purpose: This study evaluated the use of a mitogenic growth factor in combination with barrier membranes and porous alloplastic scaffolds for the repair of segmental defects of the mandible.
Materials and methods: Fifteen Göttingen minipigs were used for the study. In five animals, mandibular defects of 2 cm were created on both sides of the mandible and bridged by a system of polylactic acid (PLA) tubes and pyrolized bovine bone. On one side of the mandible, the alloplastic scaffolds were loaded with 115 microg recombinant human basic fibroblast growth factor (rhbFGF). In five other animals, defects 4 cm in length were created bilaterally, similarly bridged, and loaded with 230 microg of rhFGF. In five control animals, bilateral 2-cm defects were created that were left empty on one side and bridged with an empty PLA tube on the other. Mitogenic efficacy of the growth factor was assessed on fibroblast cultures by di-methyl-thiazol-2-tetrazolium-bromide assay before implantation.
Results: After 5 months, there was negligible bone regeneration in the control defects, regardless of whether they had been left completely empty or bridged by empty PLA tubes. The 2-cm defects showed bridging in 8 of 10 tubes, with complete consolidation by bone ingrowth in four defects. The 4-cm defects showed bony union in six cases, with complete bone fill in two tubes, and four defects incompletely filled. The bFGF had no appreciable effect with regard to velocity, quantity, and three-dimensional structure of bone formation, neither in the short nor in the long defects despite clear in vitro efficacy.
Conclusion: Repair of segmental defects using bioresorbable membranes appears to be possible. However, a single-dose application of bFGF is apparently ineffective, possibly because of rapid dilution.