Examination of the duration of vitamin B12 administration for hypoesthesia caused by inferior alveolar nerve injury after horizontally impacted mandibular third molar: A retrospective study

Objective This study aimed to assess the time to cure of hypoesthesia caused by inferior alveolar nerve (IAN) injury after horizontally impacted mandibular third molar (M3) extraction under continuous administration of mecobalamin, a vitamin B12 preparation, and factors that influence the time to cure. Methods This was a single-center retrospective study including 33 patients who experienced hypoesthesia after horizontally impacted M3 extraction and were treated with continuous oral administration of mecobalamin alone. The patients were divided into cured (n = 28) and uncured groups (n = 5). Demographic and clinical data were collected and analyzed. Results Of the 33 patients, 5 (15 %) reported uncured hypoesthesia. The median time to cure of hypoesthesia with mecobalamin administration was 33 (range, 6–202) days, and no cure beyond 7 months was reported. Age (≥30 years), Pell and Gregory classification (Position), and presence of Rood and Shehab signs ("interruption of white line of canal" and "diversion of canal") were significantly associated with prolonged time to cure. Conclusions It may be necessary to evaluate the efficacy of mecobalamin for IAN injury after horizontally impacted M3 extraction approximately 30 days after the initiation of administration and consider treatment modification or additional treatment within approximately 7 months.