China Journal of Oral and Maxillofacial Surgery ›› 2025, Vol. 23 ›› Issue (2): 129-136.doi: 10.19438/j.cjoms.2025.02.005

• Original Articles • Previous Articles     Next Articles

Analysis of sagittal jaw movements and pharyngeal airway changes in skeletal Class Ⅱ patients following bimaxillary surgery

WU Jia-qing, SHEN Ai-li, QIAN Yi-feng, LIU Jia-qiang   

  1. Department of Oral and Craniomaxillofacial Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine; College of Stomatology, Shanghai Jiao Tong University; National Center for Stomatology; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology; Shanghai Research Institute of Stomatology. Shanghai 200011, China
  • Received:2024-10-24 Revised:2024-11-28 Online:2025-03-20 Published:2025-04-06

Abstract: PURPOSE: To explore the relationship between jaw movements and changes in pharyngeal airway morphology and volume by studying the preoperative and postoperative jaw movements and pharyngeal airway alterations in skeletal Class Ⅱ patients undergoing bimaxillary surgery. METHODS: A total of 28 skeletal Class Ⅱpatients with maxillary protrusion and mandibular retrusion who received orthognath-orthodontic combined treatment in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from January 2021 to June 2024 were selected. All patients underwent maxillary setback via Le Fort I osteotomy combined with mandibular advancement using bilateral sagittal split ramus osteotomy(BSSRO). The difference in sagittal movement of the mandible was defined by subtracting the maxillary retraction from the mandibular forward movement. According to the difference of sagittal movement of the mandible,the patients were divided into two groups: group A(n=14) with a sagittal movement difference > 0 mm, and group B (n=14) with a sagittal movement difference ≤; 0 mm. All patients received CT scans at the end of preoperative orthodontics (T0) and six months after orthognathic surgery(T1). The CT data were imported into Dolphin Imaging 11.9 software to measure pharyngeal airway morphological parameters and jaw movements. Statistical analysis was performed using SPSS 29.0 software package. RESULTS: In group A, the sagittal movement difference was positively and linearly correlated with oropharyngeal airway volume. In group B, the sagittal movement difference had a nonlinear relationship with oropharyngeal airway volume. When the sagittal movement difference was less than -1.24 mm(R2=0.8225, P< 0.05), -1.02 mm(R2=0.6670, P< 0.05), -1.34 mm(R2=0.7717, P< 0.05), and -1.17 mm(R2=0.7332, P< 0.05), the total pharyngeal airway volume, nasopharyngeal airway volume, oropharyngeal airway volume, and hypopharyngeal airway volume decreased, respectively. CONCLUSIONS: In skeletal ClassⅡ patients undergoing maxillary setback combined with mandibular advancement, when the amount of maxillary setback exceeds the amount of mandibular advancement by more than 1 mm, there is significant reduction in pharyngeal airway volume. Therefore, for skeletal Class Ⅱ patients with a predisposition to pharyngeal airway narrowing, the treatment plan should be appropriately adjusted to mitigate airway risks.;

Key words: Skeletal Class Ⅱ malocclusion, Orthognathic surgery, Pharyngeal airway space, Sagittal jaw movements

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