Evaluation of a Custom Three‐Dimensional Surgical Guide in Mandibular Sagittal Split Osteotomy: An Exploratory Split‐Mouth Randomized Controlled Trial

OBJECTIVE: This exploratory split-mouth randomized controlled trial aimed to evaluate the effect of a custom three-dimensional (3D) surgical guide on mandibular sagittal split osteotomy outcomes compared with conventional freehand osteotomy. METHODS: Patients undergoing sagittal split osteotomy (SSO) were randomly assigned in a split-mouth design to receive mandibular osteotomy performed with a custom-made 3D surgical guide on one side and without a surgical guide on the contralateral side. The primary outcome was the postoperative lingual split scale (LSS) of the mandible. Secondary outcomes were lateral osteotomy end (LOE), assessed using postoperative CT-based evaluation, and intraoperative inferior alveolar nerve exposure (NE). RESULTS: Fifteen patients contributed 30 mandibular sides for paired analysis. Guided sides showed more favourable LSS (p = 0.041) and LOE (p = 0.041) distributions compared with non-guided sides. No statistically significant difference was observed in NE (p = 0.763). These findings suggest that the use of a custom 3D surgical guide may improve osteotomy control and split predictability. CONCLUSION: The custom 3D surgical guide was associated with more favourable lingual split pattern and lateral osteotomy end distributions during sagittal split osteotomy. Given that the study population consisted predominantly of skeletal Class III patients, these findings should be interpreted primarily within the context of Class III patients. No significant reduction in intraoperative inferior alveolar nerve exposure was observed.