Statistical Analysis of Orthognathic Surgery Undertaken in the Oral and Maxillofacial Surgery Department of Yamagata University Hospital over the Past 28 Years

Purpose: To perform a statistical analysis of orthognathic surgery performed at the Oral and Maxillofacial Surgery Department of Yamagata University Hospital between 1990 and 2017. Methods : Sex, age, clinical diagnosis, surgical method, operation time, bleeding volume, and postoperative management of 583 patients were analyzed. Results : There were 190 males and 393 females. The age at the time of surgery ranged from 5 to 73 years (average age 22.0 years). Mandibular protrusion alone was the most frequent clinical diagnosis, accounting for 278 cases (47.7%), followed by 99 cases of facial asymmetry with mandibular protrusion (17.0%), and 45 cases of open bite with mandibular protrusion (7.7%). A total of 384 cases (67.1%) of sagittal split ramus osteotomy (SSRO) and 140 cases (24.5%) of double-jaw surgery using SSRO and Le Fort I osteotomy (LF I) were performed. There were 20 cases (3.5%) of genioplasty (GEN) concomitant with SSRO. In recent years, double-jaw surgery has been the most frequent surgical procedure. The average surgical time and bleeding volume were 162.8min and 278.9ml in SSRO respectively, and 310.1min and 767.6ml in LF I+SSRO respectively, and both decreased over time. The number of days patients stayed in hospital was on a downward trend, with the shortest stay being 6 days, the longest 40 days, and the average 17.9 days. For occlusion management after surgery, no cases have been fixed with wire since 2010, and intermaxillary rubber traction was used in all cases. With regard to congenital diseases, 9 patients with cleft lip and palate, one with Apert syndrome, and one with Pfeiffer syndrome were treated. Discussion : In spite of the increase in complicated surgical procedures in recent years, operating time, hospitalization time and bleeding volume have decreased. These trends may signify improvements in surgical techniques and perioperative management. Because almost all of our cases are referrals from other dental clinics, the constant trend in the number of surgeries indicates smooth cooperation with regional medical facilities.