Purpose: Condylar orientation in the glenoid housing is a critical and most demanding step after proximal segment separation in mandibular setback surgery, as it affects postoperative skeletal stability and occlusion. This study aimed to assess the proximal segment position after fixation using surgical guides and pre-bent plates compared to the manual free hand proximal segment seating.

Methods: Twenty patients with skeletal class III malocclusion were randomly allocated to two groups. Both proximal and distal segments were repositioned using osteotomy/screw holes and plate locating surgical guides with pre-bent plates osteosynthesis in the intervention group, while manual free hand proximal segment positioning was performed in the control group.

Results: Proximal segment position after fixation was assessed using computed tomography. Bodily and angular condylar deviation was significantly lower for the intervention group (X-axis: 0.03 ± 0.02, Y-axis: 0.02 ± 0.03, Z-axis: 0.03 ± 0.03 mm), (Axial: 0.24 ± 0.28, Coronal: 0.24 ± 0.19, Sagittal: 0.29 ± 0.13°) compared to the control group (X-axis: 1.38 ± 0.48, Y-axis: 1.35 ± 0.51, Z-axis: 1.66 ± 0.15 mm), (Axial: 2.79 ± 1.51, Coronal: 3.14 ± 2.28, Sagittal: 2.49 ± 1.40°).

Conclusion: Computer guided approach significantly decreased proximal segment displacement compared to the manual free hand technique.