Review the Impact of Mandibular Setback Surgery for the Correction of Class III Malocclusion on the Upper Airway Space

AIM: This study aimed to review the scientific evidence related to the effect of mandibular setback surgery for the correction of Class III malocclusion on the changes in volume and anatomical structures’ positions of the upper airway within at least 1 year follow-up. METHODS: An electronic research was conducted on PubMed, Google scholar, and Elsevier up to April 20, 2021, the inclusion criteria were prospective or retrospective studies aiming to compare the changes in upper airway space following isolated mandibular setback through at least 1 year of follow-up. RESULTS: A total of 84 studies were retrieved, only 12 studies met the eligibility criteria. Their methods of measurement were using lateral cephalometry, CT, or Cone-beam computed tomography. Most of them showed narrowing in the Pharyngeal airway space, with some variability within the follow-up periods. Impact on the possibility of obstructive sleep apnea (OSA) was discussed in most of the included studies. CONCLUSION: Narrowing of upper airway volume is associated with isolated mandibular setback surgeries within 1 year of follow-up. However, OSA was not necessarily a consequence. Any predisposing factors for OSA should be considered before isolated mandibular setback surgery.

Postoperative changes in the pharyngeal airway space through computed tomography evaluation after mandibular setback surgery in skeletal class III patients: 1-year follow-up

Background This study evaluated the pharyngeal airway space changes up to 1 year after bilateral sagittal split osteotomy mandibular setback surgery and bimaxillary surgery with maxillary posterior impaction through three-dimensional computed tomography analysis. Methods A total of 37 patients diagnosed with skeletal class III malocclusion underwent bilateral sagittal split osteotomy setback surgery only (group 1, n = 23) or bimaxillary surgery with posterior impaction (group 2, n = 14). Cone-beam computed tomography scans were taken before surgery (T0), 2 months after surgery (T1), 6 months after surgery (T2), and 1 year after surgery (T3). The nasopharynx (Nph), oropharynx (Oph), hypopharynx (Hph) volume, and anteroposterior distance were measured through the InVivo Dental Application version 5. Results In group 1, Oph AP, Oph volume, Hph volume, and whole pharynx volume were significantly decreased after the surgery (T1) and maintained. In group 2, Oph volume and whole pharynx volume were decreased (T2) and relapsed at 1 year postoperatively (T3). Conclusion In class III malocclusion patients, mandibular setback surgery only showed a greater reduction in pharyngeal airway than bimaxillary surgery at 1 year postoperatively, and bimaxillary surgery was more stable in terms of airway. Therefore, it is important to evaluate the airway before surgery and include it in the surgical plan.

Multislice computed tomography assessment of airway patency changes in the supine position following mandibular setback surgery for mandibular prognathism: A prospective 1-year follow-up study

Objectives: The purpose of this study was to perform a three-dimensional analysis on the pharyngeal airway of supine patients who have undergone mandibular setback surgery, using multislice computed tomography (MSCT). We also measured the respiratory disturbance index pre- and post-surgery, using a portable sleep monitor. Materials and Methods: The subjects included two males and nine females who were diagnosed with mandibular prognathism at Hiroshima University Hospital and were scheduled to undergo the bilateral sagittal split osteotomy. Using a CT scanner, baseline MSCT images were obtained from the subjects before surgery for morphological analysis, and then the two further scans were obtained after mandibular setback surgery. All patients were provided with at-hoeme sleep monitor to use it both at baseline and approximately 1 year after surgery. Results: Middle and epiglottis pharyngeal space and cross-sectional area were significantly decreased immediately after setback surgery, but did not change further over the 1-year period. Mandibular setback was not associated with the development of sleep breathing disorder (SBD) during the 1-year follow-up period. Conclusion: We found no evidence that the reduction in the pharyngeal airway space immediately after mandibular setback surgery recovered significantly during the follow-up period, although mandibular setback was not associated with development of SBD.

Airway cephalometric change following mandibular setback surgery: a review article

Background and Aim: mandibular setback surgery is one of the common treatments in patients with mandibular prognathism. In this surgery, the mandible is placed backward from its original position, and as a result, the soft tissue, tongue, and hyoid bone are slightly displaced, all of which can affect the dimensions of the airway. Given that these changes in the dimensions of the airway can lead to obstructive sleep apnea, it is important to examine these changes and their stability. In this regard, cephalometric radiography can be used, which haslowcost and dose in comparison to 3D radiographs, to examine changes in airway dimensions. The aim of this study was to evaluate the short-term and long-term changes in airway dimensions following mandibular steback surgery with the help of cephalometric radiography. Methods: The study was conducted by review method. Using the keywords 'orthognathic surgery,' 'mandibular setback,' 'Malocclusion angle class III,' 'prognathism,' 'airway,' 'posterior airway space,' 'PAS,' 'pharyngeal space, 'hypopharynx, a review of articles in PubMed and Embase databases, Google Scholar, and Cochranedatabases was performed. The range of article searches was from 2000 to 2020. Conclusion: The results of studies showed that in the first 6 months after surgery, the dimensions of the airway decrease, but over time, due to the adaptation of the surrounding tissues and relapse after surgery, there is an improvement in the dimensions of the airway; Also, the study of index-related breathing disorders during sleep disorders during sleep showed that this surgery does not necessarily lead to obstructive sleep apnea.