Background <p>Minimally invasive thyroid surgery offers cosmetic benefits over traditional approaches, but mental nerve injury risk affecting the chin and lower lip persists. Transoral endoscopic thyroidectomy within a defined safety zone is a scarless alternative that may cause transient sensory changes.</p> Methods <p>In this prospective observational study, 77 patients with benign thyroid conditions were enrolled; after exclusions, 37 underwent transoral endoscopic thyroidectomy and 40 underwent conventional transcutaneous thyroidectomy. Baseline chin and lower lip sensation was quantified preoperatively and postoperatively at 1&#xa0;week, 1&#xa0;month, and 2&#xa0;months using a monofilament evaluator, measuring the area of sensory deficit at 1&#xa0;mm intervals. The conventional group served as a control, as this approach is not associated with mental nerve injury.</p> Results <p>Baseline sensation was normal in both groups. The mean patient age was 32.5 ± 8.9&#xa0;years (53% female). Operative times were significantly longer in the transoral group. All 37 transoral patients experienced transient sensory disturbances immediately postoperatively. The area of sensory deficit decreased at 1 and 2&#xa0;months compared with 1&#xa0;week (<i>p</i> = 0.028), and 5 of 37 patients achieved complete recovery by 2&#xa0;months, while the remaining patients demonstrated progressive reduction in affected area. No sensory changes occurred in the conventional group at any time point.</p> Conclusions <p>Transoral endoscopic thyroidectomy within a defined safety zone induces early transient sensory disturbances that improves or resolves by 2&#xa0;months postoperatively. These findings support its use as a safe, cosmetically superior alternative to conventional thyroidectomy, with minimal long-term compromise to mental nerve integrity.</p> Graphical abstract <p></p>