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Background Mandibular setback surgery can change the position of the mandible which improves occlusion and facial profile. Surgical movement of the mandible affects the base of the tongue, hyoid bone, and associated tissues, resulting in changes in the pharyngeal airway space. The aim of this study was to analyze the 3-dimensional (3D) changes in the hyoid bone and tongue positions and oropharyngeal airway space after mandibular setback surgery. Methods A total of 30 pairs of cone-beam computed tomography (CBCT) images taken before and 1 month after surgery were analyzed by measuring changes in the hyoid bone and tongue positions and oropharyngeal airway space. The CBCT images were reoriented using InVivo 5.3 software (Anatomage, San Jose, USA) and landmarks were assigned to establish coordinates in a three-dimensional plane. The mean age of the patients was 21.7 years and the mean amount of mandibular setback was 5.94 mm measured from the B-point. Results The hyoid bone showed significant posterior and inferior displacement ( P < 0.001, P < 0.001, respectively). Significant superior and posterior movements of the tongue were observed ( P < 0.05, P < 0.05, respectively). Regarding the velopharyngeal and glossopharyngeal spaces, there were significant reductions in the volume and minimal cross-sectional area ( P < 0.001). The anteroposterior and transverse widths of the minimal cross-sectional area were decreased ( P < 0.001, P < 0.001, respectively). In addition, the amount of mandibular setback positively correlated with the amount of posterior and inferior movement of the hyoid bone ( P < 0.05, P < 0.05, respectively). Conclusion There were significant changes in the hyoid bone, tongue, and airway space after mandibular setback surgery.

BackgroundTo evaluate the three-dimensional (3D) changes after mandibular setback surgery (MSS) in skeletal Class III malocclusion using cone-beam computed tomography (CBCT) and a structured light-based scanner.MethodsTwenty-eight adult Korean patients with skeletal Class III malocclusion treated by MSS were evaluated. CBCT and facial scan images were recorded one week before and six months after surgery. To use an identical 3D coordinate system, superimposition was performed, and nine skeletal and 18 soft tissue landmarks were identified. Changes in the landmarks and correlation coefficients and ratios between hard and soft tissue changes were evaluated. Paired t test and Pearson’s correlation test were performed.ResultsAfter MSS, the amount of transverse correction was 2.45 mm; mandibular setback, 5.80 mm; and vertical reduction, 1.64 mm at the menton, on average. In the transverse axis, there were significant changes and correlations in the lips and chin and an increasing gradient of ratios from the lower lip to the chin. In the anteroposterior axis, the lower lip and chin moved backward significantly and showed notable correlation with hard tissue movement. In the vertical axis, significant upward movement was observed in the landmarks related to the chin, but only lower facial height was significantly decreased.ConclusionsSoft tissue changes according to hard tissue movement after MSS exhibited a distinct pattern of an increasing gradient from the lips to the chin in a transverse aspect.

Introduction: Mandibular setback surgery (MSS) is one of the treatment options to resolve mandibular prognathism in patients suffering from skeletal class III malocclusion, which cannot be treated with simple orthodontic treatment. The mandibular setback surgical operation can involve changes in the pharyngeal morphology, resulting in a narrowing of the posterior airway space (PAS). This aspect is associated with an increase in airflow resistance, which increases the risk of developing snoring or obstructive sleep apnea syndrome (OSAS). The aim of this study is to evaluate the medium- and long-term effects of mandibular setback surgery on the upper airways and its possible association with OSAS in patients suffering from class III skeletal malocclusion. Material and methods: A total of 12 patients (5 males and 7 females) were enrolled in this study. The statistical tests highlighted a significant change in the PAS and BMI values in relation to T0, before surgery (PAS: 12.7 SD: 1.2; BMI: 21.7 SD: 1.2), and T1, after surgery (PAS: 10.3 SD: 0.6, p < 0.01; BMI: 23.8 SD: 1.2, p < 0.05). Sample size was calculated to detect an effect size of 0.9, with statistical power set at 0.8 and the significance level set at 0.05. Results: No statistically significant correlation was found between the extent of mandibular setback, PAS and BMI change. Conclusion: This study confirms the effects of mandibular setback surgery on the upper airways, reporting a statistically significant PAS reduction in the medium- and long-term follow-up. On the other hand, no direct correlation was identified with OSAS risk, at least for the small mandibular setback (<8 mm), despite the statistically significant increase in BMI.

The aim of this study was to evaluate the effects of a partial glossectomy on volumetric changes of pharyngeal airway space (PAS) in patients with mandibular setback surgery. Overall, 25 patients showing clinical features related to macroglossia treated with mandibular setback surgery were included in this retrospective study. Subjects were divided into two groups: the control group (G1, n = 13, with BSSRO) and the study group (G2, n = 12, with both BSSRO and partial glossectomy). The PAS volume of both groups was measured by the OnDemand 3D program on CBCT taken shortly before operation (T0), 3 months post-operative (T1), and 6 months post-operative (T2). A paired t-test and repeated analysis of variance (ANOVA) were used for statistical correlation. Total PAS and hypopharyngeal airway space were increased after operation in Group 2 compared to Group 1 (p < 0.05), while oropharyngeal airway space showed no significant statistical difference with the tendency of increasing. The combination of partial glossectomy and BSSRO surgical techniques had a significant effect on increasing the hypopharyngeal and total airway space in class III malocclusion patients (p < 0.05).

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.

Introduction The changes in length and height of tongue following mandibular setback (MS) surgery may affect pharyngeal airway dimensions. There is limited literature correlating tongue dimensional changes with linear and volumetric airway changes following MS with bilateral sagittal split ramus osteotomy (BSSRO) in skeletal class III patients. Materials and Methods Treatment records of 18 patients who underwent MS with BSSRO were evaluated for changes in tongue and linear airway dimensions, mean airway volume and area at T1 (1-week pre-surgery), T2 (6-month post-surgery) and T3 (2-year post-surgery). Amount of MS was recorded from case sheets of patients. Mean tongue length reduced, whereas mean tongue height increased at T2 compared to T1 ( P value = 0.001 for both). Linear, area and volumetric airway parameters at T2 were significantly reduced ( P value = 0.001). All parameters showed statistically nonsignificant increase from T2 to T3 ( P value > 0.05). Correlation analysis showed that change in tongue length at T3 did not show statistically significant correlation with amount of MS, changes in linear, area and volumetric airway parameters ( P value > 0.05). However, the change in tongue height at T3 showed a significant ( P value < 0.05) negative correlation ( r value = − 0.742) with change in posterior airway space (PAS). Conclusions The appraisal of tongue length and height after MS surgery should be an integral part of diagnosis and treatment planning. The retro-positioning of tongue and increase in its height after MS surgery may compromise pharyngeal airway especially PAS. Additional options such as bi-jaw surgery, debulking of tongue volume and genioplasty should be explored to minimize adverse effects post-surgically.

Background and Objectives: The most popular surgical procedures among orthognathic surgeries for Class II and III patients are Le Fort 1 osteotomy for the maxilla and bilateral sagittal split ramus osteotomy (BSSRO) for the mandible. Keeping the condyle in its proper place during fixation is one of the difficulties of orthognathic surgery. One of the worst post-orthognathic surgery consequences in the temporomandibular joint (TMJ) area may be condylar resorption. Condylar remodeling refers to a group of processes that occur in reaction to forces and stress placed on the temporomandibular joint in order to preserve morphological, functional, and occlusal balance. A systematic review of the literature was performed with the aim of identifying the mandibular condylar component of TMJ changes after orthognathic surgery in class II and III patients. Materials and Methods: An electronic search was carried out using the PubMed, Cochrane Library, and Google Scholar, databases. The inclusion criteria included trials in non-growing patients upon whom orthognathic surgery was performed due to Angle II or Angle III classes malocclusion; in addition, a CT or cone beam computed tomography (CBCT) scan was performed before and after surgery to track the mandibular condylar component of TMJ changes. The quality of the studies was evaluated by two independent authors. The risk of bias was assessed by using the Downs and Black checklist. Results: The electronic and manual literature search yielded 12 studies that fulfilled all necessary inclusion criteria. Observed studies were evaluated as good (3), fair (8), and poor (1) quality. Two studies evaluated class II patients, six studies observed class III patients, and four studies were comparative. Most of the studies evaluated condyle angle and space changes, and the condylar surface and volume changes were also observed. However, the methodology of evaluation in the publications differs. Conclusions: Reduction of bone density, especially in class II patients, and morphological condyle reshaping, with the apposition of the bone, is the main adaptive mechanism after orthognathic surgery. However, all of the studies we examined were conducted using different methods of evaluation, measurement, and reference points.

Objective This study aimed primarily to evaluate three-dimensionally the alteration in the temporomandibular joint (TMJ) at short- and long-term follow-up after mandibular advancement (MAS) and mandibular setback (MSS) surgeries; secondarily to compare these changes between the two surgical interventions. Materials and methods Forty-six patients (92 TMJs) were analyzed: 23 patients underwent MAS, and 23 patients received MSS. Computed tomography scans were obtained preoperatively (T0), within one week postoperatively (T1), and at two years postoperatively (T2). A validated three-dimensional TMJ assessment protocol, encompassing condylar position, inclination, dimensions, joint spaces, intra-articular alignment, and volumetric joint space was applied, and appropriate statistical tests were used to compare changes across time intervals and between the two interventional groups. Results In the MAS group, the mediolateral inclination angle of the right condyle significantly changed from T0 to T1 by 5.56 ± 0.9°, then increased at T2 with a mean long-term change of 0.59 ± 0.14°. Condylar height on the left side also decreased significantly ( p  = 0.020). Superior (SJS) and posterior joint spaces (PJS) of the left TMJ were reduced by 1.18 ± 0.23 and 0.72 ± 0.29 mm, respectively, whereas in the MSS group, only the anterior joint space (AJS) of the right TMJ increased between T1 and T2 by 0.24 ± 0.09 mm. Volumetric joint space decreased significantly after MAS and remained stable after MSS. No significant changes were reported between the two types of surgeries, except for AJS, SJS, mediolateral condylar position, and anteroposterior condylar position ( p  < 0.05). Conclusion MAS showed measurable condylar positional changes, mainly lateral inclination and mild posterior displacement, whereas MSS demonstrated smaller within-group changes. However, inter-group analyses indicated greater changes in selected TMJ parameters after MSS than MAS. These findings, based solely on radiographic assessments, warrant cautious interpretation.

This review evaluated literature on soft tissue changes in patients following bilateral sagittal split osteotomy (BSSO) for mandibular advancement or setback. Twenty published articles were identified for further analysis. The included articles related to patient cohorts ranging between 12 and 109 participants, the age range of 14–68 years, with a majority of female patients, and follow-up periods in the range of 6–114 months. The primary outcomes were soft tissue changes in the cephalometric soft tissue points; pogonion (Pg'); menton (Me'); labrale inferius (Li); and mentolabial fold (B'). Soft-to-hard tissue ratios varied widely across both conventional and alternative mandibular procedures, with higher ratios observed for advancement in the conventional group. For example, at pogonion (Pg’) in advancement cases, ratios ranged from 80 – 133%. This study highlights the complexity of soft tissue changes following bilateral sagittal split osteotomy (BSSO). The variability seen in outcomes underscores the need for longer follow-up periods and surgery after skeletal growth has waned. Despite the valuable insights gained from the literature, considerable variability underscores the influence of skeletal relapse, age, and fixation type. Standardized long-term 3D studies are warranted to refine predictive models when isolated BSSO is performed.

Objective This study assessed 2-year oropharyngeal airway changes in skeletal Class II patients following isolated mandibular advancement by bilateral sagittal split osteotomy (BSSO) with or without maxillary setback by Le Fort I osteotomy (Le fort I). Materials and methods Cone-beam computed tomography (CBCT) data from 25 isolated BSSO and 57 BSSO + Le fort I patients were retrospectively analyzed at three stages: preoperatively (T0), 3 months (T1), and 2 years postoperatively (T2). The total upper airway volume (V), minimum cross-sectional area (CSA min ), and volumes of the nasopharynx (V NA ), velopharynx (V VE ), and glossopharynx (V GL ) were measured via Dolphin Imaging. Results Isolated BSSO significantly increased V, CSA min , V NA , V VE , and V GL by 38.86%, 69.49%, 22.31%, 46.05%, and 46.94%, respectively, at T1 ( P  < 0.01) and 21.85%, 43.11%, 13.85%, 19.73%, and 25.38%, respectively, at T2 ( P  < 0.05). From T1 to T2, V, CSA min , V VE , and V GL decreased by 12.24%, 15.56%, 18.02%, and 14.67%, respectively ( P  < 0.05). Multivariate regression revealed that each 1 mm advancement of the PNS and B points increased V by 1038 mm³ and V VE by 519 mm³; PNS advancement increased V NA by 708 mm³ ( P  < 0.05). Compared with BSSO + Le fort I, isolated BSSO yielded greater short-term improvements (V: +11175 vs. +3638 mm³; P  < 0.001) and superior long-term stability in V and V NA ( P  < 0.05). Notably, the combined advancement of PNS and B point may be a robust predictor for postoperative changes of the upper airway volume. Conclusion Isolated BSSO induces sustained upper airway expansion for 2 years, which is driven primarily by hard tissue advancements. Compared with BSSO + Le fort I, this technique has superior short- and long-term efficacy, providing guidance for the optimized management of skeletal Class II patients. Ethics approval This study was approved by the Ethics Committee of Peking University Stomatological Hospital (Approval No. PKUSSIRB-202167121).