Evaluation of bone formation after sagittal split ramus osteotomy with bent plate fixation using computed tomography

Area of Science:

• Oral and Maxillofacial Surgery
• Orthognathic Surgery
• Bone Regeneration

Background:

• Sagittal split ramus osteotomy (SSRO) is a common procedure in orthognathic surgery.
• Plate fixation is used to stabilize bone segments after osteotomy.
• Understanding bone formation in the osteotomy gap is crucial for predicting long-term stability.

Purpose of the Study:

• To evaluate bone formation between proximal and distal segments following SSRO with bent plate fixation.
• To compare bone healing using titanium versus absorbable plates.
• To assess changes in ramus dimensions post-SSRO.

Main Methods:

• Bilateral SSRO setback surgery was performed on 23 patients (46 sides).
• A 3-7 mm gap was created and stabilized with bent titanium or absorbable plates.
• Computed tomography (CT) was used to measure ramus dimensions (square, anteroposterior length, mediolateral width) preoperatively, immediately post-surgery, and at 1 year.

Main Results:

• No significant differences in bone formation or dimensional changes were observed between titanium and absorbable plate groups.
• Ramus square (RmS) increased significantly at 1 year post-surgery in both groups.
• Anteroposterior ramus length (RmA-RmP) increased immediately post-surgery and decreased at 1 year, but remained larger than preoperative values.

Conclusions:

• New bone formation effectively fills the gap after SSRO with bent plate fixation, irrespective of plate material (titanium or absorbable).
• Significant bone regeneration occurs even with minimal bony contact between the osteotomy segments.
• The study demonstrates the potential for bone healing in SSRO gaps stabilized with bent plates.