In this study, we conducted a clinical analysis of 1,239 patients with jaw deformities who had undergone orthognathic surgery at our hospital over the 22 years from January 2001 to December 2022. The participants included 450 male and 789 female patients with a mean age of 26.8 years （range, 13-65 years） at the time of surgery. Various surgical methods are used at our hospital, the two most common being sagittal split ramus osteotomy （SSRO） and combined Le Fort Ⅰ osteotomy with SSRO （LF-1＋SSRO）. The average operative time for SSRO was 188.8min, whereas that for LF-1＋SSRO was 296.7min. The average blood loss after SSRO was 346.1mL, whereas that after LF-1＋SSRO was 325.8mL. Improvements in postoperative stability and facial appearance have become increasingly important. Furthermore, LF-1＋SSRO procedures have become more complex, leading to an increase in average operative time.

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Patients with skeletal Class Ⅱ malocclusion often undergo mandibular advancement surgery. However, to reduce stress on the mandibular condyle and temporomandibular joint, it is also possible to perform maxillary orthognathic surgery alone, planned with counterclockwise autorotation of the mandible to improve the relationship between the maxillary and mandibular jaws and occlusion. We herein report a case of successful treatment outcomes by performing maxillary orthognathic surgery alone in a patient with skeletal Class Ⅱ high-angle malocclusion.
A 17-year-old female presented with complaints primarily related to chin retrusion and crowding, along with tension in the mentalis muscle during lip closure and a convex facial profile with a gummy smile. The diagnosis was skeletal Class Ⅱ malocclusion with significant clockwise rotation of the mandible and lingual inclination of the mandibular anterior teeth. The molar relationship was Angle Class Ⅰ, with an overjet of ＋5.0mm, overbite of ＋1.0mm, and arch length discrepancy of −1.0mm in the maxilla and −4.0mm in the mandible.
After extracting both mandibular first premolars and conducting preoperative orthodontic treatment for 1 year 4 months, we performed maxillary horseshoe osteotomy combined with Le Fort Ⅰ osteotomy and ge­ni­o­plas­ty. The maxilla was moved 3.5mm upward in the anterior region and 4.5mm upward and 5.0mm backward in the molar region. As a result, the mandible rotated 3.5 degrees counterclockwise. Postoperative orthodontic treatment commenced immediately after surgery, and retention started thereafter. The tension in the mentalis muscle during lip closure decreased, resulting in a harmonious facial profile. Although the molar relationship became Class Ⅲ, satisfactory coverage and tight occlusion were achieved. At 5 years 6 months after the start of retention, a slight clockwise relapse of the mandible was observed, but good occlusion was maintained.
Maxillary orthognathic surgery alone, by moving the maxilla upward and backward, resulted in coun­ter­clock­wise rotation of the mandible, anterior movement of the chin, and an improved facial profile. In addition to the favorable treatment outcomes, the stability of the mid-term prognosis suggests that maxillary orthognathic surgery alone is an effective approach for Class Ⅱ skel­e­tal malocclusion.

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