Morphological changes in the pharyngeal airway of female skeletal class III patients following bimaxillary surgery: A cone beam computed tomography evaluation

Postsurgical Volumetric Airway Changes in Class III Patients Receiving Bimaxillary Orthognathic Surgery

The purpose of the present study was to investigate the pharyngeal airway space (PAS) changes in class III patients receiving bimaxillary orthognathic surgery and correlate the PAS volume and minimum axial section changes with the magnitude of the surgical movement. This research involved a retrospective sample composed of 38 patients with class III skeletal occlusions. Three-dimensional measurements of the PAS volume and minimum axial section were conducted. Cephalometric points were used to verify the extent of jaw-hyoid bone movement. No significant differences were found between pre and postoperative total PAS volume (P = 0.280), nasopharyngeal volume (P = 0.545), oropharyngeal volume (P = 0.297), and minimum axial section (P = 0.568). Anterior movement of point A and posterior nasal spine were significantly associated with an increase in total PAS volume, oropharyngeal volume, and minimum axial section (P < 0.05). However, the posterior movement of menton was significantly associated with a decrease in total PAS volume, oropharyngeal volume, and minimum axial section (P < 0.05). The results of the present study indicated that PAS is not negatively affected by bimaxillary surgery in class III patients. However, the planning of class III patients who are prone to the development of airway problems should be done carefully.

Pharyngeal airway subdivisions in 3-dimensional analysis: Differences between anterior and posterior anatomic boundaries

INTRODUCTION

This study aimed to evaluate if there were differences between anterior and posterior anatomic boundaries used for the 3-dimensional determination of pharyngeal airway.

METHODS

The sample included 150 cone-beam computed tomography scans from healthy patients divided according to (1) age: 6-11, 12-16, and ≥16 years; (2) sex: female and male; (3) anteroposterior skeletal pattern: Class I, II, and III; (4) vertical pattern: brachyfacial, mesofacial, and dolichofacial; and (5) craniocervical inclination (CCI): natural head posture, head flexion, and head extension. Anatomic regions were created to determine the correspondences between structures anteriorly and posteriorly to the pharyngeal airway.

RESULTS

The location of the epiglottis, vallecula, hyoid, C2, and C3 were statistically different according to the CCI, and the location of vallecula, C3, and C4 were different according to sex. However, no statistically significant differences were observed between the frequencies of anterior and posterior anatomic region locations among age and different anteroposterior and vertical skeletal patterns. Posterior landmarks tend to be located below the anterior ones; consequently, the anatomic subregion they define will also be located below.

CONCLUSIONS

Anterior and posterior structures and vertical and anteroposterior skeletal patterns may determine upper airway limits regardless of age. However, the studies must be paired according to sex, and CCI must be standardized.

Quantification of pharyngeal airway space changes after two-jaw orthognathic surgery in skeletal class III patients

BACKGROUND

Skeletal class III malocclusion is a common dentofacial deformity. Orthognathic treatment changes the position of the jaws and affects the shape of the upper airway to some extent. The aim of this study was to use multislice spiral computer tomography data and orthognathic knowledge to quantify the relationship between the amount of surgical movement of the maxilla or mandible in all three spatial planes and the changes in airway volume that occurred.

METHODS

A retrospective study of 50 patients was conducted. Preoperative and postoperative linear changes related to skeletal movements of the maxilla and mandible were measured and compared to changes in the most constricted axial level (MCA) and its anteroposterior (MCA-AP) and transverse diameters (MCA-TV). Correlation tests and linear regression analysis were performed.

RESULTS

Significant interactions were observed between the anterior vertical movement of the maxilla and the MCA-AP. The anteroposterior movement distance of the mandible was significantly correlated with changes in the oropharyngeal, velopharyngeal, total airway volume, MCA, MCA-AP, and MCA-TV. The change in the mandibular plane angle was significantly correlated with the change in velopharyngeal volume, total airway volume (nasopharynx, oropharynx, velopharynx), and MCA. The linear regression model showed that oropharyngeal volume decreased by 350.04 mm³, velopharyngeal volume decreased by 311.50 mm³, total airway volume decreased by 790.46 mm³, MCA decreased by 10.96 mm² and MCA-AP decreased by 0.73 mm² when point B was setback by 1 mm.

CONCLUSIONS

Anteroposterior mandibular control is the key to successful airway management in all patients. This study provides estimates of volume change per millimeter of setback to guide surgeons in treatment planning.

Three-Dimensional Evaluation of Upper Airway Changes After Bimaxillary Surgery of Skeletal Class 3 Patients

The aim of this study was to evaluate the 3-dimensional changes in upper airway space of class 3 patients after surgery with sleep-related breathing disturbance. This is a retrospective cohort study included 25 patients who had undergone bimaxillary orthognathic surgery with maxillary advancement and mandibular setback for skeletal class 3 deformity. The changes in minimum axial area, nasopharyngeal and oropharyngeal airway volume were determined by cone-beam computed tomography images, as well as the sleep parameters by polysomnography preoperatively and postoperatively. The impacts of mandibular setback and maxillary advancement amounts on the airway structures were evaluated and compared with other parameters. The results show that pharyngeal volume measurement means were found to be significantly increased postoperatively (P<0.05). No significant difference was observed in the mean values of minimum axial area and sleep parameters after the operation (P>0.05). A positive relationship was determined between the oropharyngeal volume and minimum axial area changes at a rate of 60% (r: 0.600). No relationship was revealed between airway volume changes and polysomnographic parameters. An increase in the total airway volume and no postoperative sleep-related disturbance symptoms were observed in the patients treated by maxillary advancement and mandibular setback surgery.

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.

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.

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.

Long-term three-dimensional effects of orthognathic surgery on the pharyngeal airways: a prospective study in 128 healthy patients

OBJECTIVE

To investigate volumetric and circumferential pharyngeal airway space (PAS) changes and stability over time as evaluated with cone beam computed tomography (CBCT) before and after orthognathic surgery 2 years postoperatively.

MATERIALS AND METHODS

One hundred twenty-eight patients underwent bimaxillary orthognathic surgery at the Department of Maxillofacial Surgery of University Hospitals, Leuven, Belgium, were recruited prospectively. Patients were divided into 4 groups based on the amount of mandibular advancement in 5 mm increments (< 0 mm, 0-5 mm, 5-10 mm, or > 10 mm). CBCT data was acquired preoperatively and 1-6 weeks, 6 months, 1 year, and 2 years postoperatively. Patients with a history of maxillofacial trauma or surgery, obstructive sleep apnoea syndrome, or craniofacial anomalies were excluded. Nasopharyngeal, oropharyngeal, and hypopharyngeal PAS volumes and constriction surface areas (mCSA) were measured and compared between each time point with a paired t-test.

RESULTS

The largest significant increase in oropharyngeal volume and mCSA were observed in the 5-10 mm (+ 13.3-21.7%, + 51.3-83.0%)) and > 10 mm (+ 23.3-44.6%, + 92.3-130.0%) mandibular advancement groups. This increase only remained stable 2 years postoperatively in the > 10 mm group. In other mandibular advancement groups, short-term oropharyngeal volume and mCSA increases were noticed, which returned to baseline levels 6 months to 1 year postoperatively.

CONCLUSION

Bimaxillary advancement osteotomy significantly increases oropharyngeal volume and mCSA, which remains stable between 6 months to 1 year postoperatively.

CLINICAL RELEVANCE

Long-term stable volumetric and mCSA enlargements were found with > 10 mm mandibular advancements over a period of 2 years. Return towards baseline levels was observed in the other mandibular advancement groups.

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.

Upper Airway Changes Following Different Orthognathic Surgeries, Evaluated by Cone Beam Computed Tomography: A Systematic Review and Meta-analysis

PURPOSE

This study sought to assess the upper airway changes following different orthognathic surgeries using cone-beam computed tomography.

METHODS

An electronic search of the literature was conducted in major electronic databases including Medline (PubMed), Web of Science, Scopus, and Open Grey for articles published up to January 20, 2018. Human studies that evaluated the changes in the volume and minimum cross-sectional area of the upper airway or its subdivisions in patients who had undergone orthognathic surgery by use of cone-beam computed tomography were included. Manual search of the bibliographies of the included articles was also conducted. The included studies underwent risk of bias assessment.

RESULTS

A total of 1330 articles were retrieved. After excluding the duplicates and irrelevant articles, 41 studies fulfilled the eligibility criteria for this systematic review; out of which, 30 entered the meta-analysis. The majority of studies had a medium risk of bias. Mandibular setback, and maxillary advancement + mandibular setback decreased the volume of the upper airway (-6042.87 mm3 and -1498.78 mm3, respectively) and all its subdivisions in long-term (>3 months), except for the nasopharynx, the volume of which increased following maxillary advancement + mandibular setback. Mandibular advancement and maxillomandibular advancement both increased the upper airway volume in long-term (7559.38 mm3 and 7967.06 mm3, respectively); however, only the changes after the former procedure were significant. The minimum cross-sectional area increased after maxillomandibular advancement (161.43 mm2), and decreased following maxillary advancement + mandibular setback (-23.79 mm2) in long-term.

CONCLUSION

There is moderate evidence to suggest that mandibular advancement is the only orthognathic movement that provides a statistically significant change in long-term upper airway volume.

A Modified Cosmetic Genioplasty Can Affect Airway Space Positively in Skeletal Class II Patients: Studying Alterations of Hyoid Bone Position and Posterior Airway Space

BACKGROUND

Improving the posterior airway space is one of the most important functions of genioplasty. Studies have shown that the posterior airway space (PAS) can play an important role in the evaluation of obstructive sleep apnea syndrome (OSAS). The purpose of this study is to evaluate the airway safety of our modified technology by observing the impact on PAS in skeletal Class II patients without OSAS.

METHODS

We have modified a cosmetic genioplasty, which can guarantee the continuity of the lower edge of the bilateral mandible by rotating the chin segment clockwise. Fourteen patients submitted to our modified cosmetic genioplasty alone were included in the study. The facial convexity angle and the ratio of the face were measured by analyzing photographs. The position of the hyoid bone and the width of the PAS were measured by analyzing lateral cephalograms. The volume and the cross-sectional area (CSA) of the PAS were measured using 3D reconstruction. The Wilcoxon signed-rank test and paired samples t test were used to assess the significance of differences of the data (p < 0.05).

RESULTS

Soft tissue measurements were statistically different (p = 0.001) and achieved satisfactory results. The position of the hyoid bone moved up (L_X: p = 0.004; L_ML: p = 0.056) and forward (L_Y: p = 0.001; L_CV3: p = 0.016). The increase in the CSA had statistical significance (p < 0.005). There were significant statistical differences in the total airway volume and hypopharynx (p = 0.001), except in the oropharynx (p = 0.096).

CONCLUSIONS

Our modified genioplasty not only achieved better cosmetic results by ensuring the continuity of the lower edge of the bilateral mandible but also exerted a significant positive impact on the posterior airway space for patients with skeletal class II, thus helping reduce the prevalence of OSAS. We hence suggest performing this modified cosmetic genioplasty on the skeletal class II patients with/without OSAS if necessary.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Why most patients do not exhibit obstructive sleep apnea after mandibular setback surgery?

Maxillomandibular advancement (MMA) is effective for the treatment of obstructive sleep apnea (OSA). In previous studies, the airway was increased in the anteroposterior and transverse dimensions after MMA. However, the effect of the opposite of mandibular movement (mandibular setback) on the airway is still controversial. Mandibular setback surgery has been suggested to be one of the risk factors in the development of sleep apnea. Previous studies have found that mandibular setback surgery could reduce the total airway volume and posterior airway space significantly in both the one-jaw and two-jaw surgery groups. However, a direct cause-and-effect relationship between the mandibular setback and development of sleep apnea has not been clearly established. Moreover, there are only a few reported cases of postoperative OSA development after mandibular setback surgery.

These findings may be attributed to a fundamental difference in demographic variables such as age, sex, and body mass index (BMI) between patients with mandibular prognathism and patients with OSA. Another possibility is that the site of obstruction or pattern of obstruction may be different between the awake and sleep status in patients with OSA and mandibular prognathism. In a case-controlled study, information including the BMI and other presurgical conditions potentially related to OSA should be considered when evaluating the airway. In conclusion, the preoperative evaluation and management of co-morbid conditions would be essential for the prevention of OSA after mandibular setback surgery despite its low incidence.

Silent Changes in Sleep Quality Following Mandibular Setback Surgery in Patients with Skeletal Class III Malocclusion: A Prospective Study

Mandibular setback surgery (MSS) for skeletal class III patients can result in a relative reduction of pharyngeal airway space (PAS). Consequently, there is a possibility of the decline of sleep quality after surgery. We investigated changes in sleep quality measured by overnight polysomnography (PSG) and the three-dimensional (3D) volumes of PAS following MSS with or without Le Fort I osteotomy (LF I) in class III patients (N = 53). Overnight PSG and cone beam computed tomography were conducted at preoperative stage (T0) and postoperative 3 months (T1). Measurements of PAS volumes were performed, and the subjective symptoms of sleep were evaluated by self-questionnaires. There were significant increases in respiratory disturbance index (RDI) and total respiratory effort-related arousal (RERA) index during T0-T1. The 3D volumes of PAS showed significant decreases in the oropharyngeal airway, hypopharyngeal airway, and total airway spaces. No significant changes were observed in subjective symptoms of sleep. MSS with or without LF I for class III patients could worsen sleep quality by increasing sleep parameters such as the RDI and RERA in PSG, and reduce volumes of PAS at postoperative 3 months. Although subjective symptoms may not show significant changes, objective sleep quality in PSG might decrease after MSS.

Reliability of upper pharyngeal airway assessment using dental CBCT: a systematic review

Background

Upper airway analysis is an often-cited use of cone beam computed tomography (CBCT) imaging in orthodontics. However, the reliability of this process in a clinical setting is largely unknown.

Objective

Our objective was to systematically review the literature to evaluate the reliability of upper pharyngeal airway assessment using dental CBCT.

Search methods

MEDLINE, EMBASE, Web of Science, and Google Scholar were searched through June 2015.

Selection criteria

Human studies that measured reliability of upper airway assessment in patients using CBCT as part of the study protocol were considered.

Data collection and analysis

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) was followed. Data were collected on overall study characteristics and measurements, CBCT unit and machine settings used, and examination characteristics of the included studies. Methodological quality of the included studies was evaluated.

Results

Forty-two studies were evaluated, representing the CBCT scans of 956 patients. Studies included a wide variety of patients and CBCT machines with various scan settings. Only five studies were deemed high quality. The available evidence indicates that under specific restricted conditions there is moderate to excellent intra- and inter-examiner reliability. Airway volume demonstrated greater intra- and inter-examiner reliability than did minimum cross-sectional area. However, significant methodological limitations of the current literature, most importantly a lack of manual orientation of the images and selection of threshold sensitivity in study protocols, suggest that reliability has not been adequately established.

Conclusions

The current literature reports moderate to excellent reliability, with airway volume having higher reliability than minimum cross-sectional area. However, only limited aspects of the process of airway analysis have been evaluated, indicating that further research is required to adequately establish the reliability of upper pharyngeal airway assessment of patients using dental CBCT.

Registration

None.

The structural changes of pharyngeal airway contributing to snoring after orthognathic surgery in skeletal class III patients

BACKGROUND

Two-jaw surgery including mandibular and maxillary backward movement procedures are commonly performed to correct class III malocclusion. Bimaxillary surgery can reposition the maxillofacial bone together with soft tissue, such as the soft palate and the tongue base. We analyzed changes of pharyngeal airway narrowing to ascertain clinical correlations with the prevalence of snoring after two-jaw surgery.

METHODS

A prospective clinical study was designed including a survey on snoring and three-dimensional (3D) computed tomography (CT) in class III malocclusion subjects before and after bimaxillary surgery. We conducted an analysis on changes of the posterior pharyngeal space find out clinical correlations with the prevalence of snoring.

RESULTS

Among 67 subjects, 12 subjects complained about snoring 5 weeks after the surgical correction, and examining the 12 subjects after 6 months, 6 patients complained about the snoring. The current findings demonstrated the attenuation of the largest transverse width (LTW), anteroposterior length (APL), and cross-sectional area (CSA) following bimaxillary surgery given to class III malocclusion patients, particularly at the retropalatal level. The average distance of maxillary posterior movements were measured to be relatively higher (horizontal distance 3.9 mm, vertical distance 2.6 mm) in case of new snorers.

CONCLUSIONS

This study found that bimaxillary surgery could lead to the narrowing of upper airway at the retropalatal or retroglossal level as well as triggering snoring in subjects with class III malocclusion. Based on the current clinical findings, we also found that upper airway narrowing at retropalatal level may contribute to increasing the probability of snoring and that polysonography may need to be performed before orthognathic surgery in subjects with class III malocclusion.

Three-dimensional analysis of the pharyngeal airway space and hyoid bone position after orthognathic surgery

PURPOSE

The aim of this study was to evaluate changes in the pharyngeal airway space (PAS) and hyoid bone position after orthognathic surgery with cone-beam computed tomography (CBCT).

MATERIAL AND METHODS

This study was conducted with the tomographic records of 30 patients with skeletal class II or III deformities submitted to two different types of orthognathic surgery: Group 1 (n = 15), maxillary advancement, and mandibular setback; and Group 2 (n = 15), maxillomandibular advancement. CBCT scans were acquired preoperatively (T₀); and at around 1.5 months (T₁) and 6.7 months (T₂) postoperatively. PAS volume, minimum cross-sectional area (min CSA), and hyoid bone position changes were assessed with Dolphin Imaging 3D software, and results analyzed with ANOVA and a Tukey-Kramer test (p < 0.05).

RESULTS

The hyoid bone was significantly displaced in the horizontal dimension, moving posteriorly in Group 1, and anteriorly in Group 2. Although PAS volume and min CSA increased after both surgeries, these measurements were significantly larger only in Group 2. The significant differences that existed between groups preoperatively no longer existed after the surgeries.

CONCLUSIONS

Both orthognathic surgeries assessed resulted in changes in hyoid bone position and increased PAS volume and min CSA, particularly after maxillomandibular advancement surgery.

The structural changes of upper airway and newly developed sleep breathing disorders after surgical treatment in class III malocclusion subjects

Bimaxillary surgery is the traditional treatment of choice for correcting class III malocclusion which is reported to cause an alteration of oropharyngeal structures and upper airway narrowing that might be a predisposing factor for obstructive sleep apnea (OSA). This study aimed to analyze sleep parameters in class III malocclusion subjects and ascertain the prevalence of snoring or OSA following bimaxillary surgery.A total of 22 patients with Le Fort I osteotomy and mandibular setback for class III malocclusion were prospectively enrolled. All patients received endoscopic examination, cephalometry, 3-dimensional computed tomography (3D-CT), and sleep study twice at 1 month before and 3 months after surgery.The patient population consisted of 5 males and 17 females with a mean body mass index of 22.5 kg/m and mean age of 22.1 years. No patients complained of sleep-related symptoms, and the results of sleep study showed normal values before surgery. Three patients (13%) were newly diagnosed with mild or moderate OSA and 6 patients (27%) showed increased loudness of snoring (over 40 dB) after bimaxillary surgery. According to cephalometric analysis and 3D-CT results, the retropalatal and retroglossal areas were significantly narrowed in class III malocclusion patients, showing snoring and sleep apnea after surgery. In addition, the total volume of the upper airway was considerably reduced following surgery in the same patients.Postoperative narrowing of the upper airway and a reduction of total upper airway volume can be induced, and causes snoring and OSA in class III malocclusion subjects following bimaxillary surgery.

Sleep-disordered breathing following mandibular setback: a systematic review of the literature

INTRODUCTION

A mandibular setback reduces space in the pharyngeal airway, and it has been suggested that it might induce sleep-disordered breathing.

OBJECTIVES

An evidence-based literature review was conducted to identify the effect of mandibular setback on the respiratory function during sleep.

METHODS

The authors performed a systematic review of pertinent literature published up to 2014. A structured search of literature was performed, with predefined criteria. A survey of the PubMed, ScienceDirect, and Cochrane database was performed. A manual search of oral and maxillofacial surgery-related journals was accomplished. Potentially relevant studies then had their full-text publication reviewed.

RESULTS

A total of 1,780 publications were evaluated, through which nine papers (seven case series and two case-control studies) were selected for the final review. No evidence of sleep disorder after six months was related in 223 patients. In one study, two patients developed obstructive sleep apnea syndrome after surgery, and in another two studies, seven patients presented an increase of obstructive apneas/hypopneas events and oxygen desaturation index. Most of the patients analyzed were young and thin.

CONCLUSION

There was no evidence of postoperative sleep apnea syndrome after a mandibular setback surgery. However, one should always consider a potential reduction of the upper airway space during the treatment plan. Obese patients and those submitted to large amounts of mandibular setbacks present a higher chance to develop obstructive sleep apnea syndrome.

Three-Dimensional Evaluation of the Upper Airway Morphological Changes in Growing Patients with Skeletal Class III Malocclusion Treated by Protraction Headgear and Rapid Palatal Expansion: A Comparative Research

Objective

The aim of this study was to evaluate the morphological changes of upper airway after protraction headgear and rapid maxillary expansion (PE) treatment in growing patients with Class III malocclusion and maxillary skeletal deficiency compared with untreated Class III patients by cone-beam computed tomography (CBCT).

Methods

Thirty growing patients who have completed PE therapy were included in PE group. The control group (n = 30) was selected from the growing untreated patients with the same diagnosis. The CBCT scans of the pre-treatment (T1) and post-treatment (T2) of PE group and the control group were collected. Reconstruction and registration of the 3D models of T1 and T2 were completed. By comparing the data obtained from T1, T2 and control group, the morphological changes of the upper airway during the PE treatment were evaluated.

Results

Comparing with the data from T1 group, the subspinale (A) of maxilla and the upper incisor (UI) of the T2 group were moved in the anterior direction. The gnathion (Gn) of mandible was moved in the posterior-inferior direction. The displacement of the hyoid bone as well as the length and width of dental arch showed significant difference. The volume and mean cross-sectional area of nasopharynx, velopharynx and glossopharynx region showed significant difference. The largest anteroposterior/the largest lateral (AP/LR) ratios of the velopharynx and glossopharynx were increased, but the AP/LR ratio of the hypopharynx was decreased. In addition, the length and width of the maxillary dental arch, the displacement of the hyoid bone, the volume of nasopharynx and velopharynx, and the AP/LR ratio of the hypopharynx and velopharynx showed significant difference between the data from control and T2 group.

Conclusion

The PE treatment of Class Ⅲ malocclusion with maxillary skeletal hypoplasia leads to a significant increase in the volume of nasopharynx and velopharynx.

CBCT in orthodontics: assessment of treatment outcomes and indications for its use

Since its introduction into dentistry in 1998, CBCT has become increasingly utilized for orthodontic diagnosis, treatment planning and research. The utilization of CBCT for these purposes has been facilitated by the relative advantages of three-dimensional (3D) over two-dimensional radiography. Despite many suggested indications of CBCT, scientific evidence that its utilization improves diagnosis and treatment plans or outcomes has only recently begun to emerge for some of these applications. This article provides a comprehensive and current review of key studies on the applications of CBCT in orthodontic therapy and for research to decipher treatment outcomes and 3D craniofacial anatomy. The current diagnostic and treatment planning indications for CBCT include impacted teeth, cleft lip and palate and skeletal discrepancies requiring surgical intervention. The use of CBCT in these and other situations such as root resorption, supernumerary teeth, temporomandibular joint (TMJ) pathology, asymmetries and alveolar boundary conditions should be justified on the basis of the merits relative to risks of imaging. CBCT has also been used to assess 3D craniofacial anatomy in health and disease and of treatment outcomes including that of root morphology and angulation; alveolar boundary conditions; maxillary transverse dimensions and maxillary expansion; airway morphology, vertical malocclusion and obstructive sleep apnoea; TMJ morphology and pathology contributing to malocclusion; and temporary anchorage devices. Finally, this article utilizes findings of these studies and current voids in knowledge to provide ideas for future research that could be beneficial for further optimizing the use of CBCT in research and the clinical practice of orthodontics.

Pharyngeal airway changes after mono- and bimaxillary surgery in skeletal class III patients: Cone-beam computed tomography evaluation

The aim of this study was to evaluate the two-dimensional (2D) and three-dimensional (3D) changes in the pharyngeal airway space (PAS) in 20 class III patients who underwent mono- or bimaxillary surgery using cone-beam computed tomography (CBCT). CBCT examination was obtained before surgery (T1) and at least 3 months after surgery (T2). The pharyngeal airway of each patient was studied at three levels: the level of the posterior nasal spine, the level of the most inferior point of the soft palate, and the level of the top of the epiglottis. At each of these levels, the anteroposterior and lateral dimension as well as cross-sectional area were measured. The volume of the whole PAS and volume between each cross section were also measured. The area and anteroposterior dimensions at the level of the most inferior point of the soft palate significantly decreased in patients who underwent monomaxillary surgery. The volume of the PAS decreased in both groups, but decreased significantly only in the monomaxillary group. The upper volume decreased in the mono- and increased in the bimaxillary group. The lower volume significantly decreased in the monomaxillary group. However, results showed that PAS decreased more after mono-than after bimaxillary surgery.