Effects of bimaxillary surgery and mandibular setback surgery on pharyngeal airway measurements in patients with Class III skeletal deformities

Impacts of mandibular setback with or without maxillary advancement for class III skeletal correction on sleep-related respiratory parameters: A systematic review and meta-analysis

A systematic review and meta-analysis was conducted to evaluate the impacts of mandibular setback with or without maxillary advancement for class III skeletal correction on respiratory parameters measured by polysomnography (PSG) and to compare these respiratory parameters between these procedures for class III skeletal correction. Six electronic databases were searched up to June 2023. Studies comparing PSG parameters before and after orthognathic surgery for skeletal class III patients were selected for further analysis. The outcomes of interest were apnoea-hypopnea index (AHI), respiratory disturbance index (RDI), the lowest oxygen saturation (lowest SpO2), the average oxygen saturation (mean SpO2), and the 3% oxygen desaturation index (3% ODI). Data extraction, methodological quality assessment, risk of bias assessment, meta-analysis, and subgroup analysis were performed. Sixteen studies with a total of 476 patients who underwent orthognathic surgery for class III skeletal correction were included for meta-analysis. The risk of bias level was moderate for most studies. All PSG parameters before and after orthognathic surgery were not significantly different. The different surgical procedures also did not significantly affect post-operative PSG parameters. 5.8% of patients developed post-operative obstructive sleep apnoea (OSA). Most of them underwent a large distance of mandibular setback. There is a moderate level of evidence that mandibular setback with or without maxillary advancement for class III skeletal correction does not pre-dispose young and healthy patients to obstructive sleep apnoea when evaluated in the short term after surgery. However, post-operatively developed OSA was found in several isolated cases that underwent a large amount of mandibular setback with or without maxillary advancement.

Evaluation of Minimum Axial Airway Area and Airway Volume in Orthognathic Surgery Patients

The aim of this study was to compare preoperative and postoperative linear, planar, and volumetric measurements in the pharyngeal airway in orthognathic surgery patients. Preoperative and postoperative cone beam computed tomography (CBCT) images of 60 patients, who underwent maxillary advancement with mandibular setback (Group I, n=25) and bimaxillary advancement (Group II, n=35), were compared. The airway was divided into 3 regions as nasopharynx, oropharynx, and hypopharynx. Linear and planar measurements were made on the reference sections of each region. The minimum axial airway area, the volume of 3 regions, and total airway volume were also measured. Regarding the linear, planar, and volumetric measurements, while there was a statistically significant increase in the measurements for all three regions in Group II, in Group I only the measurements in the nasopharyngeal region demonstrated a statistically significant increase postoperatively ( P <0.05). There was an increase in minimum axial airway areas in both groups; however, it was only statistically significant in Group II ( P <0.05). There was a statistically significant increase in total airway volumes in both groups ( P <0.05). A positive and good correlation was found between the percent increase in the minimum axial area and the percent increase in the total volume ( P <0.05). While bimaxillary advancement surgery results in a significant increase in the pharyngeal airway, mandibular setback with maxillary advancement caused an increase in the total airway. Changes that may occur in the airway should be considered while planning orthognathic surgery.

Accuracy of deep learning-based upper airway segmentation

INTRODUCTION

In orthodontic treatments, accurately assessing the upper airway volume and morphology is essential for proper diagnosis and planning. Cone beam computed tomography (CBCT) is used for assessing upper airway volume through manual, semi-automatic, and automatic airway segmentation methods. This study evaluates upper airway segmentation accuracy by comparing the results of an automatic model and a semi-automatic method against the gold standard manual method.

MATERIALS AND METHODS

An automatic segmentation model was trained using the MONAI Label framework to segment the upper airway from CBCT images. An open-source program, ITK-SNAP, was used for semi-automatic segmentation. The accuracy of both methods was evaluated against manual segmentations. Evaluation metrics included Dice Similarity Coefficient (DSC), Precision, Recall, 95% Hausdorff Distance (HD), and volumetric differences.

RESULTS

The automatic segmentation group averaged a DSC score of 0.915±0.041, while the semi-automatic group scored 0.940±0.021, indicating clinically acceptable accuracy for both methods. Analysis of the 95% HD revealed that semi-automatic segmentation (0.997±0.585) was more accurate and closer to manual segmentation than automatic segmentation (1.447±0.674). Volumetric comparisons revealed no statistically significant differences between automatic and manual segmentation for total, oropharyngeal, and velopharyngeal airway volumes. Similarly, no significant differences were noted between the semi-automatic and manual methods across these regions.

CONCLUSION

It has been observed that both automatic and semi-automatic methods, which utilise open-source software, align effectively with manual segmentation. Implementing these methods can aid in decision-making by allowing faster and easier upper airway segmentation with comparable accuracy in orthodontic practice.

Influencing factors for the development of obstructive sleep apnea after orthognathic surgery in skeletal class III patients: A systematic review

This systematic review aimed to investigate the factors that may contribute to the development of OSA after orthognathic surgery in patients with skeletal class III. Electronic searches of PubMed, Embase, Web of Science, and Cochrane databases were conducted up to December 10, 2022. In total, 277 studies were retrieved and screened according to the inclusion and exclusion criteria, and 14 were finally selected. All studies were of medium quality (moderate risk of bias). The occurrence of OSA after orthognathic surgery in patients with class III skeletal relationships depends on surgical factors and patient self-factors. Surgical factors include surgery type, amount of maxillary and mandibular movement, and the patient's postoperative swelling. Patient self-factors include weight, age, gender, and hypertrophy of the soft palate, tonsils, and tongue. According to information in the 14 selected articles, the incidences of OSA after Le Fort I impaction and BSSO setback, BSSO setback, and Le Fort I advancement and BSSO setback were 19.2%, 8.57%, and 0.7%, respectively, mostly accompanied with greater amounts of mandibular recession. However, no clear evidence exists to confirm that orthognathic surgery is a causative factor for postoperative sleep breathing disorders in patients with mandibular prognathism. The wider upper airway in patients with class III skeletal might be the reason for the rare occurrence of OSA after surgery. In addition, obesity and advanced age may lead to sleep apnea after orthognathic surgery. Obese patients should be advised to lose weight preoperatively.

A retrospective analysis of redo orthognathic surgery: Underlying causes, strategy, and outcome

The aim of this study was to investigate the underlying causes of the need for redo orthognathic surgery, address surgical strategies, and evaluate postoperative outcomes. A retrospective chart review was conducted involving patients who underwent redo orthognathic surgery between January 2018 and April 2020. A total of 32 patients were included in this study. Prior to the procedures, patients' chief complaints were unfavorable facial profile, asymmetry, relapse, malocclusion, obstructive sleep apnea, and long face. To address these issues, we performed redo orthognathic surgery: this resulted in satisfactory aesthetic and functional outcomes in most cases. Considering the challenging nature of a redo orthognathic surgery, it is crucial for surgeons to accurately evaluate the patient's chief complaints and tailor individualized surgical plans to meet the patient's expectations.

Cone beam computed tomography volumetric airway changes after orthognathic surgery: a systematic review

The aim of this systematic review was to provide a structured overview of three-dimensional airway volume changes in relation to various orthognathic surgeries. Clinical human studies performing pre- and postoperative three-dimensional airway volume assessments to investigate volumetric changes of the airway after orthognathic surgery were included. Pre-determined inclusion and exclusion criteria were applied in an extensive search of the PubMed, Embase, and Web of Science electronic databases. The cut-off date was set to January 1, 2022. Forty-one articles reporting retrospective and prospective case-control and case series studies were included. All studies were determined to be of medium quality (moderate risk of bias). The included studies were categorized by type of intervention. Pre- and postoperative volumes were extracted from the available data, and volume changes as a percentage of the preoperative levels were calculated. Isolated mandibular setback surgery generally decreased the airway volume. Isolated maxillary or mandibular advancement, bimaxillary advancement, and surgically assisted maxillary expansion generally increased the airway volume in the total airway and oropharynx, among which the effect of bimaxillary advancement surgery appeared most significant. High heterogeneity exists in the terminology and definitions of the airway and its segments. A more uniform methodology for airway volume measurement is needed to provide an insight into the impact on the airway of specific types of surgical intervention. In conclusion, airway volumes are affected after orthognathic surgery, which may be of clinical significance, especially in patients who are predisposed to obstructive sleep apnoea.

Changes in the pharyngeal airway after different orthognathic procedures for correction of class III dysplasia

Objective

This study was conducted to compare changes in pharyngeal airway after different orthognathic procedures in subjects with class III deformity.

Methods

The study included CBCT scans of 48 skeletal class III patients (29 females and 19 males, mean age 23.50 years) who underwent orthognathic surgery in conjunction with orthodontic treatment. The participants were divided into three groups of 16, as follows: Group 1, mandibular setback surgery; group 2, combined mandibular setback and maxillary advancement surgery; and group 3, maxillary advancement surgery. CBCT images were taken 1 day before surgery (T0), 1 day (T1), and 6 months (T2) later. The dimensions of the velopharynx, oropharynx, and hypopharynx were measured in CBCT images.

Results

In all groups, there was a significant decrease in airway variables immediately after surgery, with a significant reversal 6 months later (P < 0.05). In subjects who underwent maxillary advancement, the airway dimensions were significantly greater at T2 than the T0 time point (P < 0.05), whereas in the mandibular setback and bimaxillary surgery groups, the T2 values were lower than the baseline examination (P < 0.05). The alterations in airway variables were significantly different between the study groups (P < 0.05).

Conclusions

The mandibular setback procedure caused the greatest reduction in the pharyngeal airway, followed by the bimaxillary surgery and maxillary advancement groups, with the latter exhibiting an actual increase in the pharyngeal airway dimensions. It is recommended to prefer a two-jaw operation instead of a mandibular setback alone for correction of the prognathic mandible in subjects with predisposing factors to the development of sleep-disordered breathing.

Computational fluid dynamic analysis of the nasal respiratory function before and after postero-superior repositioning of the maxilla

Morphological changes in the upper airway and the resulting alteration in the nasal respiratory function after jawbone repositioning during orthognathic surgery have garnered attention recently. In particular, nasopharyngeal stenosis, because of the complex influence of both jaws, the effects of which have not yet been clarified owing to postero-superior repositioning of the maxilla, may significantly impact sleep and respiratory function, necessitating further functional evaluation. This study aimed to perform a functional evaluation of the effects of surgery involving maxillary repositioning, which may result in a larger airway resistance if the stenosis worsens the respiratory function, using CFD for treatment planning. A model was developed from CT images obtained preoperatively (PRE) and postoperatively (POST) in females (n = 3) who underwent maxillary postero-superior repositioning using Mimics and ICEM CFD. Simultaneously, a model of stenosis (STENOSIS) was developed by adjusting the severity of stenosis around the PNS to simulate greater repositioning than that in the POST. Inhalation at rest and atmospheric pressure were simulated in each model using Fluent, whereas pressure drop (ΔP) was evaluated using CFD Post. In this study, ΔP was proportional to airway resistance because the flow rate was constant. Therefore, the magnitude of ΔP was evaluated as the level of airway resistance. The ΔP in the airway was lower in the POST compared to the PRE, indicating that the analysis of the effects of repositioning on nasal ventilation showed that current surgery is appropriate with respect to functionality, as it does not compromise respiratory function. The rate of change in the cross-sectional area of the mass extending pharynx (α) was calculated as the ratio of each neighboring section. The closer the α-value is to 1, the smaller the ΔP, so ideally the airway should be constant. This study identified airway shapes that are favorable from the perspective of fluid dynamics.

Quantitative changes of upper airway in class III patients undergoing bimaxillary surgery after one-year follow-up: a retrospective study

Background

Bimaxillary surgery is often performed for class III malocclusion, and its complex influence on the upper airway has been well considered. The aim of this research was to provide a scaled formula between upper airway volume changes and bone movements in Class III patients after orthognathic surgery.

Materials and methods

Using a retrospective study design, the investigators enrolled a total of 30 class III malocclusion patients who were undergoing bimaxillary surgery as the study subjects. The subjects included 15 males and 15 females, and their average age was 23.3 ± 3.4 years. CBCT (cone beam tomography) was performed both before and one year after the surgery for each patient. The changes in the soft palate, tongue and upper airway were measured by using CBCT data that was collected before and after surgery. 3D superimposition of CBCT was performed to calculate three-dimensional jaw movements. A multiple regression analysis was used to calculate the quantitative relationship between airway volume changes and jaw movements.

Results

The nasopharynx airway volume was observed to be increased by 1064.0 ± 1336.2 mm³, whereas the retropalatal and retroglossal airway volumes were observed to be decreased by 1399.0 ± 2881.6 mm³ and 1433.8 ± 3043.4 mm³, respectively, after the surgery. One millimetre forward and downward movements of the PNS resulted in increases of 626.90 mm³ and 392.18 mm³ in nasopharynx airway volume, respectively. Moreover, one millimetre retrogression of the B point caused decreases of 314.6 mm³ and 656.6 mm³ in the retropalatal and retroglossal airway volume, respectively. The changes in the soft palate contributed to the decrease in the retropalatal airway volume, whereas the tongue compensated for the decrease in the retroglossal airway volume.

Conclusion

The movements of the PNS and B points could be used to predict upper airway volumetric changes in Class III patients after maxillary advancement and mandibular setback.

Upper Airway Changes in Diverse Orthodontic Looms: A Systematic Review and Meta-Analysis

Upper airway assessment is particularly important in the daily work of orthodontists, because of its close connection with the development of craniofacial structures and with other pathologies such as Obstructive Sleep Apnea Syndrome (OSAS). Three-dimensional cone-beam computed tomography images provide a more reliable and comprehensive tool for airway assessment and volumetric measurements. However, the association between upper airway dimensions and skeletal malocclusion is unclear. Therefore, the current systematic review evaluates the effects of different surgical movements on the upper airway. Materials and Methods: Medline (PubMed, OVID Medline, and EBSCO), Cochrane Library (Cochrane Review and Trails), Web of Knowledge (social science, and conference abstracts), Embase (European studies, pharmacological literature, and conference abstracts), CINAHL (nursing and allied health), PsycInfo (psychology and psychiatry), SCOPUS (conference abstracts, and scientific web pages), and ERIC (education) databases were searched. Two authors independently performed the literature search, selection, quality assessment, and data extraction. Inclusion criteria encompassed computed tomography evaluations of the upper airway spaces with retrospective, prospective, and randomised clinical trial study designs. To grade the methodological quality of the included studies a GRADE risk of bias tool was used. Results and conclusion: In total, 29 studies were included. Among these, 17 studies had a low risk of bias, whereas 10 studies had a moderate risk of bias. A meta-analysis was performed with the mean differences using a fixed-effects model. Heterogeneity was assessed with the Q-test and the I2 index. The meta-analysis revealed significant (p ≤ 0.001, 95% confidence interval) increases in upper airway volume after rapid maxillary expansion and surgical advancement for the correction of Class II.

Comparison of oropharyngeal airway dimensional changes in patients with skeletal Class II and Class III malocclusions after orthognathic surgery and functional appliance treatment: A systematic review

Objective

To compare the dimensional changes in the oropharyngeal airway in patients with skeletal Class II and Class III malocclusion before and after orthognathic surgery and treatment with a functional appliance.

Methods

The protocol was developed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) and was registered to the International Prospective Register of Systematic Reviews (PROSPERO) under the registration number CRD42020170901. Furthermore, the reporting of the present SR was performed based on the PRISMA checklist.

Results

The use of removable functional appliances increased the volume of the oropharyngeal airway in patients with skeletal Class II malocclusion. Furthermore, the increase in the volume of the oropharyngeal airway following the removable functional appliance treatment was more than that observed after fixed functional appliance treatment in growing patients. For patients with skeletal Class III malocclusion, who underwent the bimaxillary orthognathic surgery, resulted in no change in the dimensions of the oropharyngeal airway.

Conclusion

Growing patients who receive removable functional appliance treatment have a more favorable long-term prognosis with regard to the oropharyngeal airway when compared with those who receive fixed functional appliance. Alternatively, in patients aged from (18–22) years with skeletal class III malocclusion Bimaxillary orthognathic surgery was found to be the recomended and superior method of treatment.

Three-Dimensional Evaluation of Pharyngeal Morphology in Bimaxillary Surgery with and without Horseshoe Osteotomy in Skeletal Class III Cases

Repositioning of the jaw in orthognathic treatment generates changes in the soft tissues of the maxillofacial region, with consequent changes in the airway. The purpose of this study was to determine how type of orthognathic surgical procedure affected the 3-dimensional morphology of the upper airway. Forty patients were divided into the following 2 groups according to the type of surgical procedure used: a horseshoe osteotomy (HS) group (20 patients, comprising 11 men and 9 women; average age 24.3±4.5 years) who underwent bimaxillary surgery; and a LeFort I osteotomy (LF) group (20 patients, comprising 8 men and 12 women; average age 22.5±4.6 years) who also underwent bimaxillary surgery. Cephalometric measurements were taken and 3-dimensional pharyngeal morphology evaluated in each group. The amounts of maxilla rotation, posterior maxilla impaction, and mandibular setback all revealed a significantly larger value in the HS group. Evaluation of pharyngeal volume revealed a significant decrease in the upper pharyngeal segment in the LF group. A significant decrease in the lower pharyngeal segment was observed in both groups. Differences were noted in postoperative pharyngeal morphology between the two groups. The results of this study suggest that HS has less effect on the upper pharyngeal segment, regardless of the amount of posterior maxilla impaction.

Effect of Mandibular Setback Surgery on Tongue Length and Height and Its Correlation with Upper Airway Dimensions

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.

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.

Pharyngeal airway space changes and stability following an extended LeFort-I osteotomy advancement in cleft lip and palate and non-cleft lip and palate patients: A long term comparison study

PURPOSE

The aim of this study was to evaluate effects of extended maxillary advancement osteotomy on pharyngeal airway space (PAS) in mid-facial deficient cleft lip and palate (CLP) patients and mid-facial deficient non-CLP patients.

METHODS

Pharyngeal airway space (PAS) of 10 CLP and 10 non-CLP patients with the mean age of 19 years 10 months was measured on digitized lateral cephalograms taken shortly before maxillary advancement operation with Quadrangular Le Fort I osteotomy (QLF-I) (T0), early post-operative, (T1) and long term post-operative (T2). Two way repeated analysis of variance, independent samples t-test and correlations tests were used for statistical analysis of airway and skeletal changes.

RESULTS

Total PAS depth and area was significantly increased after the advancement and was stable in long term post-operative period for CLP and non-CLP patients. Nasopharyngeal and velopharyngeal airway space depth and area was statistically increased at T1 and T2 for both groups. Oropharyngeal airway depth and area showed no significant statistical difference at any of the time points. The effect of QLF-I osteotomy on (PAS) was similar in both CLP and non-CLP patients.

CONCLUSIONS

Nasopharyngeal, velopharyngeal, and total pharyngeal airway space depth and area increased after maxillary advancement with the QLF-I osteotomy; this increase was stable in long term follow up. Maxillary advancement with the QLF-I technique had no significant effect on oropharyngeal airway space depth and area in both CLP and non-cleft patients.

Quantifying Upper Airway Changes Following Mandibular Orthognathic Surgery

ABSTRACT

The aim of this study was to quantify upper airway changes following mandibular orthognathic surgery. Treatment records of 50 patients who underwent mandibular orthognathic surgery were divided into 2 groups, that is, Group 1: Cases treated with Mandibular Advancement Surgery and Group 2: Cases treated with Mandibular Setback Surgery with 25 patients in each group. The Lateral Cephalogram and Acoustic Pharyngometry records of both groups were studied at T0 (01 week before surgery) and T1 (01 year postsurgery) for changes in linear airway measurements (Nasopharyngeal Airway Space - NAS, Superior Airway Space - SAS, Posterior Airway Space - PAS and Hypopharyngeal Airway Space (HAS)), hyoid bone position (Mandibular Plane Hyoid distance), mean area and mean volume. The percentage change and change in these parameters per millimeter advancement or setback of mandible at T1 was calculated. A significant increase in linear airway parameters (SAS and PAS); decrease in hyoid distance; and increase in volume and area of upper airway was observed at T1 in Group 1 and reverse was observed in Group 2. The change in airway parameters (SAS, PAS, mean volume and area) was more significant in Group 1 as compared to Group 2. In the current airway centric approach, meticulous assessment and prediction of long-term airway changes post surgery should be an integral part of ortho-surgical diagnosis and treatment planning and suitable modifications in the treatment plan must be made to cater for any potential adverse effects on airway.

The Effect of Bimaxillary Orthognathic Surgery on Nasalance, Articulation Errors, and Speech Intelligibility in Skeletal Class III Deformity Patients

BACKGROUND

We aimed to detect the changes in nasalance, articulation errors, and speech intelligibility after bimaxillary orthognathic surgery in skeletal class III patients.

METHODS

This double-blinded before and after quasi-experimental study was conducted in the Department of Maxillofacial Surgery, Qaem Hospital, Mashhad, Iran from Mar 2019 to Apr 2020. The main intervention was maxillary advancement with LeFort I osteotomy and mandibular setback surgery with bilateral sagittal split osteotomy (BSSO). The nasalance score, speech intelligibility, and articulation errors were evaluated one week preoperatively (T0), 1 and 6 months (T1, T2) postoperatively by a speech therapist. The significance level was set at 0.05 using SPSS 21.

RESULTS

Eleven women (55%) and 9 men (45%) with a mean age of 31.95 ± 4.72 yr were enrolled. The mean maxillomandibular discrepancy was 6.15 ± 1.53 mm. The mean scores of nasalance for the oral, nasal, and oral-nasal sentences were significantly improved postoperatively (P<0.001). Pre-operative articulation errors of consonants /r/, /z/, /s/ and /sh/ were corrected following the surgery. The percentage of speech intelligibility was significantly increased over time (P<0.001).

CONCLUSION

The patients might show a normal articulation pattern and a modified nasalance feature, following maxillary advancement plus mandibular setback surgery.

Upper airway changes following high oblique sagittal split osteotomy (HSSO)

The aim of this study was to evaluate volumetric changes of the posterior airway space (PAS) following bimaxillary surgery using a high oblique sagittal split osteotomy (HSSO) of the mandibular ramus. The cone beam CTs of Class II and Class III patients taken before (T0) and 6-12 months after surgery (T1) were analyzed using 3D software (Mimics® Innovation Suite 18.0). The PAS was divided into three segments (superior, middle, inferior) by three planes parallel to the Frankfurt horizontal plane intersecting at the posterior nasal spine, the velum palatinum and the epiglottis. Total (TPAS) and partial volumes (SPAS = superior, MPAS = middle, IPAS = inferior) were calculated. For the 25 Class II patients, a highly significant increase (p<0.001) of the total, middle and inferior airway space (TPAS: +33.6%, MPAS: +43.1%, IPAS: +55.9%) was found, while the increase of the upper airway space was statistically not significant (+5.4%, p = 0.074). For the 28 Class III patients, the total, middle and inferior airway space increased statistically insignificantly (TPAS: +4.6%, p = 0.265, MPAS: +2.7%, p = 0.387, IPAS: +2.8%, p = 0.495), while the increase of the upper airway space was statistically significant (+9.7%, p = 0.010). Bimaxillary orthognathic surgery using the HSSO technique led to a significant increase of PAS for Class II patients and could conserve the PAS for Class III patients.

Stability of single-jaw vs two-jaw surgery following the correction of skeletal class III malocclusion: A systematic review and meta-analysis

This review aims to compare the stability of sagittal skeletal and overjet anteroposterior correction of skeletal class III malocclusion in single-jaw and two-jaw orthognathic procedures. An unrestricted comprehensive electronic search was undertaken on Embase, Cochrane's CENTRAL, Web of Science, Medline, Scopus and LILACs databases up to October 2020. The bibliographies of relevant studies, ongoing, unpublished and grey literature were screened. Two independent reviewers performed study selection, bias assessment and data extraction; a third reviewer mediated inconsistencies. Randomized clinical trials, prospective cohort, retrospective cohort and series with a minimum of 1 year follow-up were eligible for inclusion. Additional subgroup analyses were undertaken. The generated effects were scored using the GRADE approach. Nine articles met the inclusion criteria and eight studies were subsequently analysed quantitatively. No significant difference in sagittal stability at the ANB angle, A-point or B-point on a short-term was detected. However, a statistically significant difference, indicating a greater short-term relapse in overjet with mandibular setbacks alone, was found (MD: -0.40 mm; 95% CI -0.77 to -0.04; I² : 0%; P = .03). Long-term follow-up (≥5 years) revealed a statistically non-significant difference in stability of sagittal skeletal and overjet corrections. Within the limitations of this review, both procedures seem to offer comparable skeletal and overjet stability outcomes; however, further high-quality research is required to confirm these findings.

Effect of Mandibular Advancement Surgery on Tongue Length and Height and Its Correlation with Upper Airway Dimensions

Introduction

The spatial position and dimensions of oral and pharyngeal soft tissues change post-mandibular advancement (MA) surgery which involves changes in position of soft palate, tongue and associated musculature. There is no study which simultaneously evaluates changes in tongue length and height post-MA surgery and correlates these changes with changes in upper airway dimensions and the amount of MA.

Materials and Methods

Treatment records of 18 patients that underwent MA with bilateral sagittal split ramus osteotomy were evaluated at T1 (01 week before surgery) and T2 (06 months post-surgery). Linear airway and tongue measurements were done on lateral cephalogram. Mean volume and mean pharyngeal area values were recorded from the acoustic pharyngometry (AP) records of patients.

Results

A statistically significant increase in tongue length (P value < 0.001) and nonsignificant change in tongue height were observed at T2 (P value > 0.05). A statistically significant increase in airway parameters recorded on both lateral cephalogram and AP was observed at T2 (P value < 0.001). Correlation analysis did not show a statistically significant correlation of change in tongue length and tongue height at T2 with the amount of MA, change in airway parameters on lateral cephalogram and AP (P value > 0.05).

Conclusions

Mandibular advancement surgery is a viable option for improvement in pharyngeal airway in skeletal Class II patients with retrognathic mandible. Changes in tongue length observed in our study may correspond to the stretch of protruders of tongue, especially genioglossus, and may point toward possible relapse on a long-term follow-up.

Is There an Increase in the Risk of Obstructive Sleep Apnea After Isolated Mandibular Setback Surgery? An Evaluation Using the STOP-BANG Questionnaire

PURPOSE

The aim of this study was to assess the impact of isolated mandibular setback surgery on the risk of obstructive sleep apnea (OSA), using the STOP-BANG questionnaire (SBQ).

PATIENTS AND METHODS

The authors implemented a double-blinded prospective quasi-experimental study. All healthy patients with skeletal Class III deformity older than 18 years were included in this study. They were candidates for isolated mandibular setback surgery. The SBQ was completed by the pulmonologist, 1 week preoperatively (T0), and 1 and 6 months postoperatively (T1 and T2, respectively). The mandibular setback displacement was the study intervention. The risk of OSA on the basis of the SBQ was the outcome variable. Descriptive and bivariate statistics were computed and the significance level was set at .05.

RESULTS

The sample comprised 30 patients (15 females, 15 males) with the average age of 25.77 ± 4.76. The mean score of SBQ at T0 was 1.37 ± 0.85, which increased to 2.33 ± 1.52 at T1 interval. However, it decreased significantly to 1.47 ± 1.17 at T2 interval (P < .001). T0-T1 and T0-T2 score differences were observed to be higher in the group with a mandibular setback repositioning greater than or equal to 5 mm (P < .005).

CONCLUSIONS

An isolated mandibular setback surgery less than 5 mm does not increase the risk for OSA in a young healthy nonsmoker Class III patient, according to the SBQ. Moreover, there was a significant increase in the risk for OSA when the setback was greater than or equal to 5 mm, measured at the mandibular incisor edge. Therefore, clinicians should be careful and discuss this potential increased risk with the patients, when this movement is required by the treatment plan. Further clinical trials are needed to support the relevancy.

Evaluation of Airway Dimensions Following Mandibular Setback with Surgery-First Orthognathic Versus Conventional Orthognathic Approach

Background

To evaluate changes in airway dimensions following mandibular setback with conventional orthognathic approach (COA) and surgery-first orthognathic approach (SFOA).

Materials and Methods

Treatment records of 20 patients who underwent mandibular setback with SFOA/COA were divided into two groups (COA and SFOA, ten patients in each group). Acoustic pharyngometry values were obtained at T0 (01 week prior to surgery), T1 (01-month post-surgery) and T2 (01-year post-surgery). Percentage change in mean volume and area was obtained at T1 (T1-T0) to evaluate airway changes and at T2 (T2-T1) to compare relapse of airway changes in both groups. Changes in airway per mm setback at T1 (T1-T0) and T2 (T2-T1) were also obtained in both groups.

Results

For both parameters, SFOA showed greater reduction at T1 and greater relapse at T2 as compared to COA. The reduction in airway volume at T1 was 0.56 mm/mm setback in COA compared to 1.06 mm/mm setback in SFOA (P-value > 0.05). The relapse in airway volume at T2 was 0.15 mm/mm setback in COA compared to 0.25 mm/mm setback in SFOA (P-value > 0.05). The reduction in area at T1 was 0.062 mm/mm setback in COA compared to 0.110 mm/mm setback in SFOA (P-value > 0.05). The relapse in area at T2 was 0.016 mm/mm setback in COA compared to 0.034/mm setback in SFOA (P-value < 0.05).

Conclusion

In setback cases, SFOA has greater airway reduction immediate post-surgically and greater relapse at 01-year follow-up. Predicting these changes at diagnostic and treatment planning stage may prevent potential adverse events on airway.

Application of Computational Fluid Dynamics Analysis after Bimaxillary Orthognathic Surgery

Bimaxillary orthognathic surgery is widely used to treat skeletal class III malocclusion. Changes in jaw position affect the shape of surrounding soft tissues. We used computational fluid dynamics (CFD) simulation to observe changes in airways observed in a patient who underwent bimaxillary orthognathic surgery. For CFD simulation, we performed cone beam computed tomography (CBCT) preoperatively (T0), 3 days postoperatively (T1), and 7 months postoperatively (T2). The values of velocity, pressure drop (ΔP), and wall shear stress all increased 7 months after surgery (Vmax 7.038 m/s to 12.054 m/s, ΔP −7.723 Pa to −53.739 Pa, WSSmax 4.214 Pa to 14.323 Pa). Locations where the velocity and pressure gradients are large included the velopharynx, oropharynx, and epiglottis, with narrow cross-sectional areas. Wall shear stress was also observed at these locations. The velopharynx, oropharynx, and epiglottis are structures most vulnerable to morphological changes, that is, they can easily become obstructed.

Postoperative complications after bimaxillary orthognathic surgery: A retrospective study with focus on postoperative ventilation strategies and posterior airway space (PAS)

PURPOSE

The aim of this study was to evaluate the impact of extubation time on postoperative complications in patients undergoing bimaxillary orthognathic surgery. We therefore retrospectively compared the effect of early extubating (EE) in the operating room versus delayed extubating (LE) on the intensive care unit (ICU) regarding postoperative complications and length of ICU/hospital stay (LOICUS/LOHS). Furthermore, we analyzed the influence of the PAS change on postoperative complications.

METHODS

The clinical data of 117 patients were retrospective analyzed regarding postoperative complications using Clavian-Dindo Classification. Volumetric calculations of the pre- and postoperative PAS were conducted using ITK-SNAP software. The Fisher's exact test was performed to evaluate the significance of differences between categorical variables. Continuous variables were analyzed using the Mann-Whitney U-Test or the Kruskal-Wallis one-way analysis of variance. Regression analysis was used estimating predictors for postoperative complications.

RESULTS

EE led to significant shortening of LOICUS (p < 0.001) and LOHS (p = 0.023). In total, we recorded 38 complications (minor n = 30; major n = 8) within the hospital stay. Complication rates were without significant differences with respect to the postoperative ventilation strategy. Large changes in PAS volume led to an increase in the major complication rates (p = 0.031). Increase or decrease of PAS was independent from postoperative complication rates (p = 1.000). Higher body mass index (p = 0.04) and a higher ASA PS score (p = 0.016) were associated with increased major complication rates.

CONCLUSION

Early extubation after surgery is a safe procedure and is associated with a reduced LOICUS and LOHS. Complications seem to occur more frequently in marked changes of the PAS and should be considered in perioperative risk stratification.

Change of the upper airway after mandibular setback surgery in patients with mandibular prognathism and anterior open bite

Purpose

It has been reported before that the amount of pharyngeal airway space (PAS) significantly decreases following mandibular setback (MS) surgery in patients with mandibular prognathism (MP). Further, MP patients with an anterior open-bite (AOB) presentation may show a larger decrease in PAS compared with those without AOB. However, studies on postoperative PAS changes in MP patients with AOB remain rare. This study sought to evaluate changes in PAS and hyoid bone positioning following MS surgery in MP patients with and without AOB.

Patients and methods

Twenty patients who underwent two jaw surgery involving MS movement were included. Patients were divided into a non-AOB group (n = 10; overbite > 2 mm) and an AOB group (n = 10; overbite < - 4 mm). Three-dimensional changes in PAS and hyoid bone positioning were compared and statistically evaluated pre- and postoperatively using computed tomography (CT).

Results

The mean magnitude of MS was 6.0 ± 2.8 mm and 5.6 ± 3.2 mm in the non-AOB group and AOB group, respectively. The oropharyngeal volume and upper hypopharyngeal volume were significantly reduced after surgery in both the groups (p = 0.006 and p = 0.003), while the retroglossal cross-sectional area was significantly reduced only in the AOB group (p = 0.028). Although the AOB group showed a larger decrease in PAS, the difference was not statistically significant between the groups. The position of the hyoid bone showed significant posterior and inferior displacement only in the AOB group, while the vertical displacement of the hyoid bone showed a statistically significant difference between the two groups.

Conclusion

PAS was significantly decreased after MS in both the groups, while only the AOB group presented a statistically significant reduction in the retroglossal cross-sectional area. Vertical displacement of the hyoid bone showed a statistically significant difference between the groups, while the PAS change was not. Surgeons should be aware of potential postoperative airway problems that may arise when performing MS surgeries.

3D Airway changes using CBCT in patients following mandibular setback surgery ± maxillary advancement

INTRODUCTION

The aim of this study was to determine the 3D airway changes that occur following mandibular setback surgery alone vs bimaxillary surgery in patients with similar skeletal start forms.

SETTING AND SAMPLE POPULATION

The University of Michigan School of Dentistry and Medical Center. A total of 85 patients undergoing mandibular setback with or without simultaneous maxillary advancement.

MATERIALS AND METHODS

A retrospective evaluation of pre- and post-surgical CBCT scans for patients undergoing mandibular setback surgery alone (14) vs bimaxillary surgery (71) was performed. Cross-sectional evaluation at standardized locations, minimum cross section and volumetric analysis were performed (Dolphin Imaging & Management Solutions).

RESULTS

Patients who underwent mandibular setback surgery alone showed a statistically significant average increase of 47.5 mm² in minimum axial area. Patients who underwent bimaxillary surgery showed a statistically significant increase in airway volume, minimum axial area, location of minimum axial area, and axial area at the retropalatal and retroglossal regions.

CONCLUSIONS

The results demonstrate that the mandible can be setback safely without decreasing airway dimensions. In borderline OSA patients, bimaxillary surgery remains the preferred approach due to the larger airway increases observed. Long-term follow-up with polysomnography must be conducted to determine the full functional implications of both procedures.

Pharyngeal Airway Modifications in Skeletal Class III Patients Undergoing Bimaxillary Advancement Surgery

PURPOSE

The purposes were to study the pharyngeal airway in patients with skeletal Class III malocclusion submitted to surgical orthodontic treatment and to correlate the alterations with bone movements.

MATERIALS AND METHODS

The sample consisted of multislice computed tomography images from 13 patients obtained before and 6 months after maxillomandibular advancement surgery. The following measurements were obtained using Dolphin Imaging software (Dolphin Imaging, Chatsworth, CA): volume and area of the oropharynx, nasopharynx, and total airway, as well as the most constricted area, anteroposterior and lateral dimensions of the narrowest axial cross-sectional area, and airway length. The paired t test was applied at a significance level of 5%.

RESULTS

Sagittal displacement of the maxilla and mandible was correlated with airway alterations using the Pearson correlation test. Alterations in airway measurements were observed in all patients after surgery. We noted a significant increase (P < .05) in total airway area, oropharyngeal area, and anteroposterior dimension of the most constricted area, as well as a significant reduction (P < .05) in airway length. A significant correlation (P < .05) was observed between nasopharyngeal area and maxillary movement and between airway length and mandibular movement (P < .05).

CONCLUSIONS

The results of this study suggest significant alterations in pharyngeal airway measurements when preoperative and postoperative periods of bimaxillary advancement surgery were compared.

The Direction of Double-Jaw Surgery Relapse for Correction of Skeletal Class III Deformity: Bilateral Sagittal Split Versus Intraoral Vertical Ramus Setback Osteotomies

Objectives

This prospective comparative clinical trial study aims to investigate the postoperative stability of the double-jaw surgical treatment of skeletal Class III deformity and to compare two different mandibular surgical approaches. The study goal is to locate the relapsing direction of both the maxilla and the distal segment after either bilateral sagittal split ramus osteotomy (BSSO), or intraoral vertical ramus osteotomy (IVRO).

Methods

Twenty-two (22) patients with skeletal Class III were included in this study. The patients were treated with double-jaw surgery by LeFort I osteotomy combined with either BSSO or IVRO. Lateral cephalograms taken before (T0), immediately after (T1), and 1 year after the surgery (T2) were studied and analyzed.

Result

The mean mandibular setback and maxillary advancement in the BSSO group were 6.22 mm at B Point and 2.93 mm at A point with relapse percentages of 24.9 and 26.6%, respectively, while the mean mandibular setback and maxillary advancement in the IVRO group were 2.55 mm at B point and 5.89 mm at A point with relapse percentages of 22.1 and 23.5%, respectively. The magnitude of the setback significantly accounted for the relapse.

Conclusion

One-year follow-up revealed that the maxilla would be displaced posteriorly and inferiorly in both groups. Regarding the direction of the mandibular relapse, the mandible in BSSO surgical group was displaced forward and upward, while in IVRO surgical group, the directions were completely different in which the mandible is displaced backward and downward.

Evaluation of Three-Dimensional Changes in Pharyngeal Airway Following Isolated Lefort One Osteotomy for the Correction of Vertical Maxillary Excess: A Prospective Study

Background

Orthognathic surgery involves movement of jaws in all three planes, and this being a part of airway complex, displacement of jaws can influence the dimension of airway at all levels. Lefort one osteotomy surgery with superior repositioning is a common procedure done for patients with vertical maxillary excess.

Purpose

The purpose of this study was to evaluate the three-dimensional volumetric changes in airway after lefort one impaction surgery using three-dimensional cone beam computed tomography (3D-CBCT) in patients with vertical maxillary excess (VME).

Methods

A prospective analysis of 15 patients who underwent isolated lefort one impaction surgery was done with pre-operative (T0) and 3-months (T1) post-operative 3D-CBCT scans. Airway was divided into three segments, nasopharyngeal, velopharyngeal and oropharyngeal. Volumetric analysis of all these segments was done before and after surgery. Paired 't test' was used to assess the mean difference in airway volume and area between T0 and T1. One-way ANOVA was used to check the mean percentage difference in airway volume and area among the three segments.

Results

The mean percentage of nasopharyngeal volume difference was - 0.6299 ± 0.9146%, velopharyngeal volume difference was - 0.5205 ± 1.107%, oropharyngeal volume difference was - 1.492 ± 2.745%. Though volume and area of pharyngeal airway were decreased after maxillary impaction surgery in all three segments of airway studied, they were not statistically significant.

Conclusion

Among the three segments of airway studied, oropharyngeal airway volume has shown the highest post-surgical reduction though statistically insignificant. ESS scores were within normal limits. Hence, we are of the opinion that there is lack of evidence to conclude that the patients undergoing lefort one superior repositioning for the treatment of VME might develop significant narrowing of PAS that may predispose the patient to breathing disorders.

Computational analysis of airflow dynamics for predicting collapsible sites in the upper airways: a preliminary study

The present study aimed to detail the relationship between the flow and structure characteristics of the upper airways and airway collapsibility in obstructive sleep apnea. Using a computational approach, we performed simulations of the flow and structure of the upper airways in two patients having different facial morphologies: retruding and protruding jaws, respectively. First, transient flow simulation was performed using a prescribed volume flow rate to observe flow characteristics within upper airways with an unsteady effect. In the retruding jaw, the maximum magnitude of velocity and pressure drop with velocity shear and vortical motion was observed at the oropharyngeal level. In contrast, in the protruding jaw, the overall magnitude of velocity and pressure was relatively small. To identify the cause of the pressure drop in the retruding jaw, pressure gradient components induced by flow were examined. Of note, vortical motion was highly associated with pressure drop. Structure simulation was performed to observe the deformation and collapsibility of soft tissue around the upper airways using the surface pressure obtained from the flow simulation. At peak flow rate, the soft tissue of the retruding jaw was highly expanded, and a collapse was observed at the oropharyngeal and epiglottis levels.

NEW & NOTEWORTHY Aerodynamic characteristics have been reported to correlate with airway occlusion. However, a detailed mechanism of the phenomenon within the upper airways and its impact on airway collapsibility remain poorly understood. This study provides in silico results for aerodynamic characteristics, such as vortical structure, pressure drop, and exact location of the obstruction using a computational approach. Large deformation of soft tissue was observed in the retruding jaw, suggesting that it is responsible for obstructive sleep apnea.

Esthetic Outcome and Airway Evaluation following Bi-Jaw Surgery V/S Mandibular Setback Surgery in Skeletal Class III Malocclusion Using Surgery First Approach

Background:

Class III skeletal deformity is the result of mandibular prognathism, maxillary deficiency, or a combination. Treatment frequently requires a combination of orthodontics and orthognathic surgical procedures to improve facial esthetics and harmonize facial profile.

Objectives:

The objective of the study is to assess and quantify, by means of cephalometric analysis, the pre- and postoperative soft-tissue and airway changes following bi-jaw surgery and mandibular setback surgery after the correction of skeletal Class III deformities using surgery-first approach.

Materials and Methods:

Patients with skeletal Class III malocclusion were classified based on the A point–nasion–B point, beta angle, and Witt's appraisal. The cases were divided based on the type of surgery-first orthognathic approach they received. Group A (20 patients) comprised patients who underwent bi-jaw surgery (Le Fort I + bilateral sagittal split osteotomy [BSSO]) and Group B (20 patients) who underwent BSSO alone. After the lateral cephalograms were digitized, the cephalograms were evaluated for soft-tissue changes and airway changes.

Results:

The soft-tissue response to simultaneous two-jaw surgery was superior to those seen in mandibular setback procedures with the exception of the changes seen in the facial contour angle and soft-tissue facial angle. There was a significant decrease in lower airway in cases treated with mandibular setback alone.

Conclusion:

Cases treated with bi-jaw surgeries had a significant soft-tissue improvement in the long term compared to mandibular setback surgeries. Since there was a significant reduction in the lower airway in cases treated with isolated mandibular surgeries, bi-jaw surgeries maybe preferred over mandibular setback surgeries.

Evaluation of posterior airway space after setback surgery by simulation

The possible negative outcomes of mandibular setback surgery (MSS) on the upper airway (UA) have become an important issue in recent years. The purpose of the present study was to compare the different amounts of MSS and to confirm the accepted maximum amount of mandibular setback by using Computational Fluid Dynamics (CFD) method. An anatomically similar UA model was constructed from magnetic resonance images of a systemically healthy individual. Two out of six models were kept as control models and the remaining four models were created to represent MSS scenarios with different amounts to correct Class III skeletal abnormality. The airflow was assumed laminar, incompressible, and the surrounding soft tissue was assumed to be linear elastic. The sixth model that was representative of 15 mm of MSS showed statistically significant differences from the other models (p < 0.05). No significant differences were observed among other models in terms of all the parameters (p > 0.05). CFD has been recently used in researches by modeling the UA flow; however, to the best of our knowledge, none of the studies have proved the maximum limits of MSS amounts with this technique. Graphical abstract ᅟ.

Apnea-Hypopnea Index in Healthy Class III Patients Treated With Intraoral Vertical Ramus Osteotomy: A Prospective Cohort Study

PURPOSE

The study purpose was to assess whether mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) induces obstructive apnea and hypopnea in healthy Class III patients without a history of respiratory dysfunction. We hypothesized that the apnea-hypopnea index (AHI) would not exceed 5 events per hour after surgery.

PATIENTS AND METHODS

A prospective cohort study was conducted. The sample was composed of healthy Class III patients without a history of obstructive sleep apnea treated with isolated mandibular setback surgery by the IVRO procedure at a university hospital. In-home respiratory sleep recordings (Nox T3; Nox Medical, Reykjavik, Iceland) and self-administered questionnaires were obtained before and at least 3 months after surgery. The AHI was the primary outcome variable. Other study variables were as follows: peripheral capillary oxygen saturation, oxygen desaturation index, snore index, body mass index, Epworth Sleepiness Scale, and Oral Impact on Daily Performance index. Descriptive and bivariate statistics were computed, and the significance level was set at .05.

RESULTS

The sample was composed of 8 patients. The mean age at surgery was 23.2 years (range, 18.2 to 33.4 years). The mean amount of surgical setback was 4.3 mm (range, 2.5 to 7.4 mm). The mean body mass index was 24.2 kg/m² (standard error [SE], 1.3 kg/m²) and 23.9 kg/m² (SE, 1.4 kg/m²) at the presurgical and postsurgical sleep recordings, respectively. The mean AHI was 1.3 events per hour (SE, 0.3; range, 0.1 to 2.5) before surgery and 1.8 events per hour (SE, 0.4; range, 0.3 to 3.3) after surgery. No statistically significant changes in AHI (P = .412), peripheral capillary oxygen saturation (P = .443), oxygen desaturation index (P = .194), snore index (P = .363), or Epworth Sleepiness Scale (P = .812) were observed. The patients' self-reported oral health-related quality of life was statistically significantly improved after surgery (P = .034).

CONCLUSIONS

Mandibular setback surgery with the IVRO procedure in the range of 2.5 to 7.4 mm did not induce obstructive sleep apnea, measured as an AHI above 5 events per hour, in the 8 healthy, young adult Class III patients presented in this study. More studies including larger patient samples are needed.

Gender differences in morphological and functional outcomes after mandibular setback surgery

PURPOSE

The aim of this study was to examine and compare morphological and functional outcomes after either isolated mandibular setback or bimaxillary surgery in males and females.

MATERIALS AND METHODS

A retrospective study was done on 52 patients, in whom surgical correction for mandibular prognathism was performed either by isolated mandibular setback (30 cases) or by bimaxillary surgery (22 cases). Morphological changes were studied using cephalograms and functional changes studied using impulse oscillometry (IOS) taken before surgery (T0), 3 months (T1) and 1 year after surgery (T2). Also 3% oxygen desaturation index (ODI) was measured at T0 and T2.

RESULT

Posterior airway space decreased significantly in both groups and both sexes but more so in males after mandibular setback surgery and in females after bimaxillary surgery. Changes in supine R20 (central airway resistance at 20 Hz) and supine R5 (total airway resistance at 5 Hz) in IOS statistically significantly increased in the period T0-T1 in males compared with females after mandibular setback surgery (p < 0.05).

CONCLUSION

Gender dimorphism is present according to morphological and functional outcomes, with males at a higher risk for obstructive sleep apnea (OSA) after mandibular setback surgery and females after bimaxillary surgery; however, compensatory changes act as a barrier against this.

Accuracy of two-dimensional pharyngeal airway space prediction for bimaxillary orthognathic surgery

PURPOSE

The aim of this retrospective study was to evaluate the accuracy of two-dimensional (2D) virtual surgical planning (VSP) of pharyngeal airway space (PAS) in patients submitted to bimaxillary orthognathic surgery.

METHODS

This study was conducted with lateral cephalograms acquired through cone-beam computed tomography records of 33 patients, divided into group 1-patients submitted to maxillary advancement and mandibular setback (n = 17) and group 2-patients submitted to maxillomandibular advancement (n = 16). Records were taken 1 to 2 months prior to surgery, which was used to perform the 2D VSP (T_p), and 6 to 8 months after surgery (T₁). In Dolphin Imaging software, the anteroposterior size of the PAS was calculated at the level of four craniometric points: A, occlusal plane (Mx), B, and pogonion (Pog). Two previously calibrated examiners performed these measurements. Statistical analyses were conducted using Kendall and t tests at a 5% level of significance.

RESULTS

There was a concordance between the two examiners at all points and times. In group 1, points A and B have statistically significant differences between the PAS measurements performed in T_p and T₁, while in group 2, none of the PAS points showed statistically significant differences when comparing T_p to T₁.

CONCLUSIONS

2D computer-based cephalometric prediction in Dolphin Imaging software offers a good orientation to professionals during the surgical procedure of bimaxillary surgeries since its use is considered clinically relevant in daily practice.