Mandibular setback by sagittal split ramus osteotomy: a 12-year follow-up

Area of Science:

• Orthognathic surgery
• Craniofacial surgery
• Skeletal cephalometry

Background:

• Mandibular setback surgery is performed to correct skeletal discrepancies.
• Bilateral sagittal split ramus osteotomy (BSSO) is a common technique for mandibular setback.
• Understanding long-term skeletal stability after BSSO is crucial for patient outcomes.

Purpose of the Study:

• To analyze short- and long-term skeletal changes following mandibular setback surgery using BSSO.
• To evaluate the stability of the mandible and identify factors influencing relapse.

Main Methods:

• Long-term cephalometric analysis of 12 patients who underwent mandibular setback surgery (mean setback 6.4 mm).
• Measurements taken up to 12 years postoperatively.
• Assessment of skeletal relapse, osteotomy slippage, condylar displacement, and proximal segment rotation.

Main Results:

• Skeletal relapse of 1 mm (14% of initial setback) occurred by the first postoperative year at B-point and pogonion (Pg).
• Osteotomy slippage, not condylar displacement or rotation, correlated with positional changes at B-point and Pg.
• The B-point and Pg remained stable from 1 to 12 years postoperatively.
• Mandibular ramus and corpus length decreased, suggesting remodeling and possible condylar resorption.

Conclusions:

• Mandibular setback via BSSO demonstrates significant stability after the first year.
• Osteotomy slippage is a key factor in early relapse.
• Long-term skeletal stability is achieved, with evidence of adaptive bone remodeling at surgical sites.