Effect of Proximal Segment Positioning on Condylar Remodeling

Bilateral sagittal split ramus osteotomy (BSSO), performed as part of bimaxillary orthognathic surgery, requires accurate positioning of the proximal mandibular segment to achieve postoperative skeletal stability and preserve temporomandibular joint function. During mandibular repositioning, discrepancies at the inferior border of the mandibular segments may be managed either by rotating the proximal segment to achieve inferior border alignment or by leveling the inferior border without rotating the proximal segment. The influence of these different positioning strategies on postoperative condylar remodeling has not been fully elucidated.

The aim of this study is to compare postoperative condylar remodeling between patients treated with proximal segment rotation for inferior border alignment and those treated with inferior border leveling without proximal segment rotation.

Condylar remodeling will be evaluated using computed tomography (CT) images obtained preoperatively, immediately after surgery, and at the 6-month postoperative follow-up. Radiological findings will be analyzed together with clinical outcomes to assess changes in condylar morphology and postoperative adaptation. The results of this study are expected to provide evidence regarding the effect of different proximal segment positioning methods on condylar remodeling and may contribute to optimizing surgical techniques in orthognathic surgery.

Inclusion criteria

• Patients with skeletal Class III dentofacial deformity scheduled to undergo bimaxillary orthognathic surgery.
• Age between 18 and 65 years.
• Patients who have completed preoperative orthodontic treatment.
• Patients in whom the mandibular distal segment demonstrates a maximum counterclockwise rotation of 4° after bilateral sagittal split osteotomy (BSSO) when positioned in the final planned occlusion.

Exclusion criteria

• History of temporomandibular joint surgery, orthognathic surgery, or tumor resection.
• Presence of facial asymmetry.
• Patients with cleft lip and/or palate, craniofacial syndromes, or a history of maxillofacial trauma.
• Patients in whom the mandibular distal segment requires more than 4° of counterclockwise rotation after BSSO to achieve the final planned position, as the amount of inferior border (basal) resection required would exceed the clinically acceptable limit.