Effects of the Le Fort I osteotomy with a U-shaped osteotomy on posterior and superior maxillary movement in skeletal Class Ⅱ malocclusion

A U-shaped osteotomy around the descending palatal artery has been developed to increase the posterior and superior movement of the maxilla after Le Fort I osteotomies in orthognathic surgery. This retrospective study evaluated the amount of maxillary movement after Le Fort I osteotomies with U-shaped osteotomies to elucidate an indication of the technique for posterior and superior movement of the maxilla. A total of 33 cases(4 men and 29 women)who underwent a Le Fort I osteotomy combined with a U-shaped osteotomy at Yokohama City University Medical Center from 2013 to 2019 were included. The duration of surgery, bleeding amount, and movement of the incisor(U1)and the first molar(U6)using lateral cephalograms before, immediately following, and one year following surgery, were evaluated. The mean duration of surgery and amount of bleeding were 413 minutes and 433.8 mL, respectively. The average and maximum posterior movements of U1 were 2.4 mm and 9.8 mm, respectively. The average and maximum superior movements of U6 were 4.0 and 8.5 mm, respectively. The accuracies of the U1 posterior and U6 superior movements were 2.4 and 1.9 mm respectively, and only the superior movement of U6 was significant compared to the preoperative position. Postoperative changes in the U1 forward-posterior direction and U6 superior-inferior direction immediately following and one year following surgery were 0.04 and 0.73mm respectively. No complications such as damage to the descending palatine artery or tooth roots were observed. These results indicated that the Le Fort I with U-shaped osteotomy can be a useful technique, securing approximately 8 mm of planned superior movement with posterior movement of the maxilla