PURPOSE: Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing missing bone segments. However, no reports have been published regarding inferior alveolar nerve regeneration during this procedure. We assumed that the nerve could regenerate with the bone regeneration during bifocal distraction, if the nerve had been saved at a mesial site of the transport disc. In the present study, we investigated that possibility in dogs. MATERIALS AND METHODS: Using a bifocal distraction osteogenesis method, we produced a 10-mm mandibular defect, including the nerve defect, and distracted the transport disc at a rate of 1 mm/day in 12 dogs. The nerve was saved at the mesial site of the transport disc. The regenerated nerve was evaluated by a jaw opening reflex examination performed once daily. Histologic examinations with hematoxylin-eosin and immunohistochemical staining with neurofilament and S-100 antibody were also performed on all dogs after death at 3, 6, and 12 months after the first operation. RESULTS: The jaw opening reflex had recovered in all dogs. The average period of recovery was 109.5 ± 24.7 days. On histologic examination, although consecutive nerves were observed in all areas, cellular nerve fascicles were seen, consistent with wallerian degeneration at 3 and 6 months in the nerve connection area on the distal side of the transport disc. CONCLUSIONS: Our results have indicated that inferior alveolar nerve regeneration after bifocal distraction osteogenesis is successful in dogs. Although our research is still at the stage of animal experiments, future application in humans can be considered to be possible.
PURPOSE: Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing missing bone segments. However, no reports have been published regarding inferior alveolar nerve regeneration during this procedure. We assumed that the nerve could regenerate with the bone regeneration during bifocal distraction, if the nerve had been saved at a mesial site of the transport disc. In the present study, we investigated that possibility in dogs. MATERIALS AND METHODS: Using a bifocal distraction osteogenesis method, we produced a 10-mm mandibular defect, including the nerve defect, and distracted the transport disc at a rate of 1 mm/day in 12 dogs. The nerve was saved at the mesial site of the transport disc. The regenerated nerve was evaluated by a jaw opening reflex examination performed once daily. Histologic examinations with hematoxylin-eosin and immunohistochemical staining with neurofilament and S-100 antibody were also performed on all dogs after death at 3, 6, and 12 months after the first operation. RESULTS: The jaw opening reflex had recovered in all dogs. The average period of recovery was 109.5 ± 24.7 days. On histologic examination, although consecutive nerves were observed in all areas, cellular nerve fascicles were seen, consistent with wallerian degeneration at 3 and 6 months in the nerve connection area on the distal side of the transport disc. CONCLUSIONS: Our results have indicated that inferior alveolar nerve regeneration after bifocal distraction osteogenesis is successful in dogs. Although our research is still at the stage of animal experiments, future application in humans can be considered to be possible.