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.