Risk factors for inferior alveolar nerve injury associated with implant surgery: An observational study

Inferior alveolar nerve (IAN) injury is the most serious complication associated with dental implant surgery, posing difficulties in treatment and potential for permanent disabilities. This study aimed to identify patient-related risk factors for IAN injury during implant placement and to investigate sensory disturbances depending on whether the implant was removed.

Twenty-eight patients with implant-related IAN injury were included. To determine risk factors, patient demographics and radiographic images were analyzed. Sensory functions were evaluated and compared based on whether the implant was removed.

IAN injury occurred more frequently in women (60.7%), with a mean age of 62.9 years. The distance from the alveolar crest to the IAN was 9.8 ± 3.0 mm, with 40.9% patients having a residual alveolar bone of 10 mm or more. The mean bone density was measured at 586.2 ± 392.5 HU, which is below the normal range for the mandible. Notably, 31.8% of the patients were found to have D4 bone. Compared to patients who did not have implants removed, those who did showed better sensory function, except pressure perception, although these differences were not statistically significant.

Older women with lower bone density were at an increased risk of IAN injury, and IAN injury occurred even in cases with sufficient alveolar ridge. The removal of implants related to the injury alone does not markedly influence the extent of sensory disturbances during follow-up period, suggesting that other aspects such as the timing of removal and severity of injury could be crucial.