Is lingual fracture pattern in sagittal split osteotomy associated with recovery of neurosensory disturbance?

BACKGROUND: Bilateral sagittal split osteotomy (BSSO) is commonly used to correct mandibular deformities but may cause neurosensory disturbance (NSD) of the lower lip due to potential injury to the inferior alveolar nerve (IAN). The purpose of this study was to evaluate the effect of LSS 3 on postoperative neurosensory disturbances. The hypothesis of this study was that the LSS 3 split pattern would extend the recovery time of neurosensory disturbance. MATERIAL AND METHODS: The retrospective cohort study included patients who underwent BSSO surgery in Erciyes University, Oral and Maxillofacial Surgery Hospital. The primary predictor variable was the lingual split pattern. The split patterns were categorized using the Lingual Split Scale (LSS). The primary outcome was NSD. The postoperative sensation was assessed using a visual analogue scale (VAS). The secondary outcome was intraoperative nerve exposure. The nerve exposure was classified as No nerve encountered, Embedded in distal segment, Embedded in proximal segment and Nerve transected. All data were analyzed using Turcosa Cloud statistical software (Turcosa Ltd. Co., Turkey). p<0.05 was considered significant. RESULTS: The study included 101 patients with 202 split sides. LSS 1 was the most common pattern (63.37%), followed by LSS 3 (25.74%). In LSS 3 split pattern, the inferior alveolar nerve mostly embedded in the proximal segment (p<0.05). NSD was highest in LSS 3 cases, particularly in the first 6 months postoperatively (p<0.05). However, no significant differences were observed after 12 months. CONCLUSIONS: LSS 3 splits may significantly increase embedded in the proximal segment and can associated with higher postoperative NSD, particularly in the first 6 months. Surgeons should consider factors contributing to LSS 3 patterns to reduce the risk of NSD.