Long-term follow-up of intersegmental displacement after orthognathic surgery using cone-beam computed tomographic superimposition

Objectives: To evaluate intersegmental displacement during long-term follow-up after bilateral sagittal split osteotomy (BSSO) by mandibular body area superimposition. Materials and Methods: Cone-beam computed tomography (CBCT) images of 23 patients ages 18 37 years with class III malocclusion before orthognathic surgery were obtained. A three-dimensional (3D) CBCT examination was performed at four stages: surgery (TO), 6 months after surgery (T1), 1 year after surgery (T2), and long-term follow-up (6.1 +/- 2.1 years, T3). The CBCT datasets were superimposed on the symphyseal area and the lower part of the distal segment of the mandible between TO and the other time points (T1, T2, and T3). The reference points (both condyle, coronoid, and sigmoid) were estimated by the CBCT analyzed program. Results: The coronoid, condylion, and sigmoid showed changes within 6 months after surgery, but there was no significant change in the intersegmental displacement between 6 months and 6 years after surgery. The distances between the left and right coronoid, condylion, and sigmoid from TO to T3 were noted. Conclusions: The change in intersegmental displacement between TO and T3 affecting relapse after orthognathic surgery was not significantly different. This suggests that the mandible itself may have a stable morphology during the follow-up period.