Effects of distraction osteogenesis on the inferior alveolar nerve of the cat mandible

Objective: In recent years, the clinical applications of distraction osteogenesis (DO) have expanded beyond conventional treatment of deformed and malformed limbs to encompass oral and maxillofacial treatment. However, few reports have described the effects of mandibular DO on the inferior alveolar nerve (IAN). The present investigation examined the long-term impact of DO on the IAN. Methods: Unilateral mandibular osteotomy was performed between the second premolar and posterior molar of cats, and a distraction device was fitted (test group). Electrophysiological tests were performed prior to osteotomy, immediately after surgery, upon completion of DO (2 weeks after surgery), and 3, 4, 5, 8, 14, 26 and 50 weeks after surgery in order to measure the shortest latency of jaw-opening reflex to direct electrical stimulation of the IAN at the mental foramen using electromyography of the digastric muscles. The remaining cats only underwent osteotomy at the same site followed by consolidation, acting as controls (control group). Results: Electrophysiological testing revealed marked increases in the latency of both the test and control groups immediately after surgery. While latency in the test group on completion of DO was virtually identical to that immediately after surgery, postoperative latency in the test group resembled latency prior to surgery. Latency in the test group tended to improve from 3 weeks after surgery, and had recovered by 14 weeks after surgery. Meanwhile, latency in the control group had recovered by 2 weeks after surgery. Conclusion: Distraction osteogenesis damages the IAN, but this damage heals over time. (C) 2012 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.