Prognostic factors for functional recovery after lingual nerve reconstruction using an artificial nerve conduit

BACKGROUND: Lingual nerve injury following dental procedures, such as lower third molar extractions, can cause significant sensory deficits. For patients with persistent severe symptoms, surgical reconstruction using a nerve conduit is often considered. However, the degree of recovery varies, and the optimal timing of intervention and the significance of the nerve gap distance remain subjects of clinical debate. OBJECTIVES: Using the Medical Research Council Scale (MRCS) as a standardized measure of sensory function, this study aims to determine the independent effects of the timing of surgery, nerve gap length, and other potential prognostic factors on nerve functional recovery, specifically defining success as MRCS S3+ or higher. METHODS: This study retrospectively analyzed a cohort of 49 patients who underwent lingual nerve repair surgery. The success of nerve recovery was evaluated using two established criteria: the standard Functional Sensory Recovery (FSR), MRCS S3 or higher, and the strict MRCS S3+ or higher criteria based on American Society of Plastic Surgeons (ASPS) criteria. The MRCS S3+ or higher criteria was designated as the primary outcome for all multivariate analyses. The time to surgery variable was logarithmically transformed, Log (Time to Surgery, months), to account for the highly skewed distribution. Statistical analysis used univariate and multivariate logistic regression to assess the association between each predictor and postoperative MRCS score. A secondary analysis examined predictors for allodynia resolution. RESULTS: The logarithmically transformed time to surgery, Log (Time to Surgery, months), was the sole statistically significant independent predictor for achieving MRCS S3+ (Odds Ratio OR = 0.236, 95% CI: 0.063-0.887, P = 0.032). This indicates that earlier intervention significantly increases the odds of functional recovery. Nerve gap length was not a significant predictor (OR = 0.941, P = 0.518). Furthermore, no variable was found to be a significant predictor for allodynia resolution (P > 0.05). CONCLUSION: Earlier surgical intervention, quantified by Log (Time to Surgery), is an independent and critical factor for achieving MRCS S3+ functional sensory recovery after lingual nerve repair. The distance of the nerve gap did not show an independent predictive effect on the final sensory outcome.