Risk Factors Associated With Inferior Alveolar and Lingual Nerve Injury Following Surgical Extraction of Impacted Mandibular Third Molars: A Retrospective Cohort Study

Introduction: Injury to the inferior alveolar and lingual nerves is a recognized complication of surgical extraction of impacted mandibular third molars and may result in temporary or permanent neurosensory disturbances. The identification of patient-, radiographic-, and procedure-related risk factors is essential for optimizing surgical planning and minimizing postoperative complications. This study aimed to evaluate the incidence of postoperative inferior alveolar and lingual nerve injuries following impacted mandibular third molar surgery and to identify the demographic, radiographic, and intraoperative factors associated with their occurrence. Methodology: This retrospective cohort study included 135 patients (165 impacted mandibular third molars) who underwent surgical extraction. Demographic characteristics, radiographic findings, and intraoperative variables were retrieved from the clinical records. Generalized estimating equations were used to account for the clustering arising from bilateral impactions. Variables that were significant on univariate analysis were entered into a multivariable model to identify independent predictors of postoperative nerve injury. Results: Postoperative neurosensory deficits occurred in 12 (7.3%) molars, including 9 (5.5%) transient and 3 (1.8%) permanent nerve injuries. Pell and Gregory Class C impactions, horizontal angulation, and radiographic overlap with the inferior alveolar canal were identified as independent predictors of nerve injury in patients aged ≥ 35 years. Prolonged surgical duration and extensive bone removal were also significantly associated with a higher incidence of postoperative neurosensory deficits, whereas root morphology and coronectomy were not significantly associated. Conclusions: Postoperative nerve injury following mandibular third molar surgery is uncommon and transient. Advanced age, deep impactions, horizontal angulation, and close radiographic proximity to the inferior alveolar canal significantly increase the risk of neurosensory complications. Careful preoperative assessment and meticulous surgical planning may facilitate risk stratification and contribute to improved surgical outcomes.