In 41 setback cases of sagittal split ramus osteotomy of the mandibular ramus with screw fixation combined with the repositioning technique for the proximal fragment, the change of the condylar position between before and after surgery wereevaluated. The movement of the condyle on a sagittal plane and the mediolateralmovement of the proximal fragments on a frontal plane were quantified with the use of lateral tomograms and frontal cephalograms taken at about the same time immediately before surgery and within 30 days after surgery.
The relations betweentemporomandibular joint disorders and the movement of the mandible and proximal fragments were also studied.
The results were as follows:
1. As for the sagittalplane, there was evidence of anterioinferior movement of the mandibular condyle after surgery. As for the frontal plane, most proximal bone fragments moved medially on the right side and laterally on the left side. The effects of these movements appeared to cancel postoperative lateral movement.
2. There wasno correlation between the lateral difference in the amount of setback and the mesiolateral movement of proximal bone fragments in a frontal plane.
3. There was no correlation between postoperative temporomandibular joint symptoms and anteroposterior and vertical movement of the condyle in a sagittal plane or the movement of proximal fragments in a frontal plane.
