In which direction is the proximal segment most likely to rotate inadvertently during a mandibular setback surgery?

During a mandibular setback surgery, the proximal segment is most likely to rotate anticlockwise. This occurs due to the surgical manipulation involved in repositioning the mandible.

In the context of this procedure, when the mandible is set back, the proximal segment tends to rotate about the occlusal plane. Usually, the condylar region is less stable, especially when the internal structures are compromised or manipulated significantly. The pulling forces from the lateral pterygoid muscle and the inherent tension on the soft tissues can contribute to this rotational movement.

An anticlockwise rotation happens because as the mandible is repositioned posteriorly, the distal occlusal surfaces remain relatively fixed while the proximal segment rotates around the pivot point near the condyle, which is positioned more anteriorly. This rotation can result in alterations in the occlusal relationship and must be taken into consideration when planning and executing the surgical procedure.

Understanding this movement helps surgeons anticipate potential complications and improve outcomes by managing the rotational forces accordingly during the surgery.