Surgical Orthodontic Treatment for Skeletal Class I with Facial Asymmetry and Occlusal Cant: A Case Report

Background: Cases of facial asymmetry with chin deviation and canted occlusal plane represent a challenge in orthodontic treatment. Case Report: We report successful surgical orthodontic treatment for skeletal Class I with severe facial asymmetry. Miniscrew anchorage was used to decompensate the canted occlusal plane in presurgical orthodontic treatment with a fixed appliance by the intrusion of the maxillary right molars and extrusion of the left molars. Then, orthognathic surgery consisting of bilateral sagittal split osteotomy for asymmetric mandibular setback was performed. Treatment resulted in marked improvement of facial asymmetry. Conclusion: The use of miniscrew implant anchorage may represent a superior presurgical orthodontic treatment and expand the possibility of treatment by one-jaw surgery.

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.

Changes in Tongue Area, Pharyngeal Area, and Pharyngeal Airway Velocity after Correction of Mandibular Prognathism

This study aimed to investigate the correlation between the amount of mandibular setback, and the related changes of the tongue area, pharyngeal area, and pharyngeal airflow velocity. Twenty-five patients treated for mandibular prognathism, and serial cephalograms were obtained (T1: preoperation, T2: more than one year postoperation). The postoperative area of the tongue, pharyngeal airway space, and pharyngeal airflow velocity were investigated. Statistical analysis was performed with the Student t-test and Pearson correlation. The amount of mandible setback was significant after surgery (12.8 mm; p < 0.001). The pharyngeal area was significantly reduced 115.5 mm2 (p = 0.046). There was a slight reduction of the tongue area (43.2 mm2; p = 0.305) and an increase of pharyngeal airflow velocity (0.3 m/s; p = 0.133). The Pearson correlation coefficient test showed no statistical significance among the amount of horizontal setback and vertical movement of the mandible, such as the reductions in the tongue area, the pharyngeal airway space, and the increase in pharyngeal airflow velocity. Larger amounts of mandibular setback caused a significant reduction of pharyngeal airway area, but without significant changes of the tongue area and pharyngeal airflow velocity.

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.

Postoperative Changes in Tongue Area and Pharyngeal Airway Space following Mandibular Setback Surgery through Intraoral Vertical Ramus Osteotomy

Purpose. The aim of this study was to determine changes in the tongue area and pharyngeal airway space (PAS) after intraoral vertical ramus osteotomy (IVRO). Materials and Methods. Serial lateral cephalograms of 40 patients with mandibular prognathism who underwent IVRO were evaluated before (T1), immediately after (T2), and more than 1 year after (T3) surgery. Paired t -tests and Pearson’s correlation analysis were used to evaluate the postoperative changes in the mandible, nasopharyngeal airway (NOP), retropalatal pharyngeal airway (RPP), retroglossal pharyngeal airway (RGP), hypopharyngeal airway (HOP), PAS, and tongue area (TA). The null hypothesis states that there are no significant correlations among the extent of mandibular setback and the changes in the TA and PAS after IVRO. Results. Immediately after the operation (T12), the mandible was set back by 12.6 mm. The NOP, HOP, and PAS were significantly reduced by 35.7 mm2, 116 mm2, and 185 mm2, respectively. The TA was increased by 69.6 mm2. The changes in PAS and TA revealed no significant difference between female and male patients at T12, T23, and T13. Moreover, no significant correlations were found among the extent of mandibular setback, TA changes, and PAS changes after IVRO. Thus, the null hypothesis was accepted. Conclusions. At the final follow-up (T13), no significant change was found in the PAS (including NOP, RPP, RGP, and HOP) and TA. The changes in PAS and TA revealed no significant difference between female and male patients at T12, T23, and T13.

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.