A Novel Intraoral Mandibular Osteotomy For Set-Back Surgery In Complex Mandibular Anatomy.

Objective: Complex mandibular anatomy including rolled-out inferior mandibular border, thin rami with cortically adherent inferior alveolar nerve (IAN) complicate the application of the current mandibular osteotomies. This study aims to introduce an intraoral Inverted-L Ramus Osteotomy (ILRO) modified with IAN lateralization and intra-canal osteotomy for management of complex mandibular anatomical variations during mandibular setback surgery.

Patients and methods: This prospective study included 20 skeletal class III patients (mean age: 21.6 ± 3.3 years) with complex mandibular anatomy indicated for mandibular setback surgery (mean setback: 6.05 ± 1.1 mm). Preoperative CBCT imaging, digital planning, and fabrication of cutting / drilling guides were performed. Surgery involved mandibular setback through the application of the ILRO modified with nerve lateralization and intra-canal osteotomy. IAN function evaluated preoperatively at intervals up to one year postoperatively. Data on bad splits and surgical duration were also analyzed.

Results: The mean surgical duration was 2.26 ± 0.21 h, with bilateral IAN exposure completed in 11 ± 3.2 min per side. All 40 osteotomy sites were separated without bad splits. Neurosensory deficits were observed in 90% of patients at two months, decreasing to 35% at six months and 5% at one year.

Conclusion: The introduced osteotomy overcomes the limitations of the traditional mandibular osteotomies in dealing with mandibular complex anatomy with adequate IAN protection and split segments integrity during mandibular setback surgery.

Clinical relevance: The introduced osteotomy provides a safe alternative to the current mandibular osteotomies utilized in mandibular setback surgery.