Comparative study of postoperative stability between conventional orthognathic surgery and a surgery-first orthognathic approach after bilateral sagittal split ramus osteotomy for skeletal class III correction

Objectives: The purpose of this study is to compare the postoperative stability of conventional orthognathic surgery to a surgery-first orthognathic approach after bilateral sagittal split ramus osteotomy (BSSRO). Materials and Methods: The study included 20 patients who underwent BSSRO for skeletal class III conventional orthognathic surgery and 20 patients who underwent a surgery-first orthognathic approach. Serial lateral cephalograms were analyzed to identify skeletal changes before surgery (T0), immediately after surgery (T1), and after surgery (T2, after 1 year or at debonding). Results: The amount of relapse of the mandible in the conventional orthognathic surgery group from T1 to T2 was 2.23±0.92 mm (P<0.01) forward movement and -0.87±0.57 mm (non-significant, NS) upward movement on the basis of point B and 2.54±1.37 mm (P<0.01) forward movement and -1.18±0.79 mm (NS) upward movement on the basis of the pogonion (Pog) point. The relapse amount of the mandible in the surgery-first orthognathic approach group from T1 to T2 was 3.49±1.71 mm (P<0.01) forward movement and -1.78±0.81 mm (P<0.01) upward movement on the basis of the point B and 4.11±1.93 mm (P<0.01) forward movement and -2.40±0.98 mm (P<0.01) upward movement on the basis of the Pog. Conclusion: The greater horizontal and vertical relapse may appear because of counter-clockwise rotation of the mandible in surgery-first orthognathic approach. Therefore, careful planning and skeletal stability should be considered in orthognathic surgery.