In total, eight IAN transposition procedures were performed in seven patients. One patient underwent bilateral surgery. Surgery was performed under general anesthesia in four patients and under local anesthesia in three patients. The IAN was lateralized for a four-tooth breadth on one side, three-tooth breadth on three sides, and two-tooth breadth on three sides. In total, 22 dental implants were placed, with an average of 3.1 implants per side (three implants in six sides and two in two sides). The residual bone height above the IAN ranged from 1 to 10 mm, with an average of 7.43 mm (SD 1.50 mm). The mean implant length was 12.77 mm (11 mm for two implants, 12 mm for five, 13 mm for 13, and 15 mm for two); the mean implant diameter was 4.45 mm (4.1 mm for five implants, 4.5 mm for 15, and 5 mm for two). All patients experienced numbness immediately and the day after surgery. All patients received short-term corticosteroid therapy(dexamethasone, Decadron^®, 6.6 mg/day) within 1 week to reduce the postoperative swelling and compression of IAN, and six patients received oral vitamin B12 (methylcobalamin, Methycobal^®, 1500 μg/day) for less than 6 months to facilitate the restoration of IAN function.

The results of our assessment of IAN function are summarized in Table 2. One patient did not respond to the recall; thus, only six patients (seven sides) were available for assessment. The median follow-up time was 49 months (range 12–105 months). No implant loss was observed during the follow-up.

Complete recovery (9 points in SW score and stage 4 in Highet grading) of neural function was observed on two side; weak hypoesthesia (7–8 points in SW score and stage 3+ in Highet grading) was observed on two sides, moderate hypoesthesia (3–6 points in SW score and stage 3+ in Highet grading) on two sides, and severe hypoesthesia (1 point in SW score and stage 2 in Highet grading) on one side. At the time of recall, three patients (four sides) were not concerned about IAN function, whereas two patients felt a slight disturbance and one patient complained of neurosensory disorder.