IAN reposition may serve as a viable treatment option in the severely resorbed mandibles. Repositioning is performed via one of the two surgical techniques, lateralization, or transposition, with lateralization yielding lower degrees of nerve deficiency. In lateralization, the IAN is exposed and retracted laterally, held in this position during implant placement, then released to rest against the implants [15]. In the transposition technique, the mental foramen is included in the osteotomy, to allow incisive branch excision, so that the IAN can be pulled into a new position, generally more posterior [16]. The advantages of IAN transposition include the ability to place longer fixtures and to engage two cortices for initial stability [3]. Further, implant insertion can occur immediately; there is no need for long waiting periods or other surgical donor sites that is sometimes required in techniques such as bone augmentation and alveolar bone distraction.

Jensen and Nock were the first to report an IAN transposition for the placement of osseointegrated implants in the posterior mandible area [5]. However, this surgical procedure involved the inherent risk of ND of the IAN. Hypoesthesia, paresthesia, and hyperesthesia are the most common postoperative complications after IAN lateralization, as observed with any surgery where a peripheral nerve is moved from its physiological site. In this study, the breadth of IAN lateralization was not associated with the occurrence of ND significantly. Some studies have evaluated the prevalence of ND after IAN lateralization surgery. Ferrigno et al. reported total ND of 21.1 % and normal neurosensory function of 73 % after 6 months of surgery [7]. Rosenquist reported that 77 % patients had no ND after 6 months of surgery and 94 % patients were normofunctional after 18 months [8]. Hashemi prospectively investigated the types and durations of ND relative to IAN lateralization and found that all patients reported ND in the first week, decreasing to 26 % at the end of the first month, and 3 % at the end of the sixth month, with no changes at the end of 1 year [9]. Fernandez Diaz and Naval Gias utilized a piezotome in IAN lateralization surgery and reported good results, with an IAN normofunctional rate of 94.7 % at 8 weeks after surgery [10]. B.M. Vetromilla reported that the patients who underwent transposition, neurosensory alterations were observed in 58.9 % of patients initially, and the condition remained for 22.1 % of those affected at the end of the study [17]. The results of these studies suggest that the risk of ND after IAN transposition or lateralization is low. However, in the present study, complete recovery of neural function at more than 1-year follow-up was observed only on one operative side, and the other patients (six of seven operative sides) reported at least a weak disturbance of IAN sensory function when evaluated by the relatively objective method.