Effects of locally applied nerve growth factor to the inferior alveolar nerve histology in a rabbit model of mandibular distraction osteogenesis.

Distraction osteogenesis (DO) is widely used in deformities and defects of the craniofacial bone. Accelerating inferior alveolar nerve (IAN) recovery would aid the process. Nerve growth factor (NGF) plays a vital role in peripheral nerve regeneration. In this study, the ability of locally applied human NGF beta (hNGFbeta) to enhance the morphological recovery of the IAN in a rabbit model of mandibular DO was studied. Rabbits underwent bilateral DO with a rate of 0.5mm per 12h. Two doses of 40 microg hNGFbeta in buffer were injected into callus at the beginning the of consolidation time. The contralateral side received injections of placebo. Rabbits were killed at 14 and 28 days. IAN specimens were subjected to histological and histomorphometric analysis. In both 14 and 28 days consolidation experiments, nerve histological analysis showed less degeneration and more regeneration in nerve fibers on the hNGFbeta treated side than the control side. Histomorphometric analysis showed that the myelinated fiber density on the hNGFbeta treated side was significantly higher than on the control side (p<0.01). The data indicate that locally applied hNGFbeta can accelerate the morphological recovery of the IAN and may play a role in reducing nerve injury in mandibular DO clinically.