Comparison of upper airway measurement by lateral cephalogram in upright position and CBCT in supine position

Upper airway and hyoid bone-related morphological parameters associated with the apnea-hypopnea index and lowest nocturnal oxygen saturation: a cephalometric analysis

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder characterized by repetitive complete or partial closure of the upper airway during sleep, resulting in sleep fragmentation and oxygen desaturation. Cephalogram is recognized as an effective diagnostic tool for predicting OSA risk in clinical practice. This study aims to assess and analyze the morphological characteristics of the upper airway and hyoid bone position associated with OSA using data from polysomnography studies and two-dimensional cephalometric analysis.

METHODS

The study included lateral cephalograms and polysomnography reports from the records of 105 adult (64 males & 41 females) patients who underwent comprehensive clinical examination. The severity of OSA was evaluated based on the apnea-hypopnea index (AHI) and lowest nocturnal oxygen saturation (LSaO2). The participants were divided into male and female groups to investigate the correlation between cephalometric parameters and OSA severity. Thirteen cephalometric parameters, including eleven linear measurements and two angular measurements, were analyzed. The significance level was set at P-value < 0.05.

RESULTS

The male group exhibited significantly higher severity of OSA compared to the female group, as indicated by higher AHI and lower LSaO2. There was an inverse association between AHI values with width of upper airway as well as distance between hyoid bone position relative to mandibular plane in both male and female groups. Additionally, only the male group showed a correlation between hyoid bone position relative to gonion/third-fourth vertebrae positions with AHI values. 4 out of 7 parameters associated with AHI in male group remained correlated with LSaO2, while in females only the distance between hyoid bone and line formed by ptergoid and pterygomaxillary fissure point showed correlation with LSaO2.

CONCLUSION

Correlation analysis revealed that a narrower upper airway was positively associated with increased AHI, while an inferiorly positioned hyoid bone in relation to mandible was negatively correlated with LSaO2. Our findings highlight the importance of several cephalometric parameters in predicting OSA severity based on AHI and LSaO2 levels; moreover, certain parameters exhibited significant gender-specific associations.

Three-dimensional evaluation of the effects of Bionator and Forsus appliances on oropharyngeal airway volume in patients with mandibular retrognathia

OBJECTIVE

To evaluate whether there is a difference between the effects of Bionator and Forsus appliances on airway volume.

METHODS

Forty patients with mandibular retrognathia were divided into two groups. The Bionator appliance was applied to Group 1, while the Forsus FRD EZ2 appliance was applied to Group 2. Three-dimensional images were captured before and after functional appliance use in both groups. Dolphin 3D software was used for airway measurements.

RESULTS

No statistically significant difference was found between the groups in terms of volumetric and area measurements. There was a statistically significant difference between the minimum axial T and O-N border T measurements of the groups.

CONCLUSION

The use of functional appliances may contribute to an increase in oropharyngeal airway dimensions, but there was no difference between the Bionator and Forsus groups in terms of volumetric measurements.

Deep Learning Models for Automatic Upper Airway Segmentation and Minimum Cross-Sectional Area Localisation in Two-Dimensional Images

OBJECTIVE

To develop and validate convolutional neural network algorithms for automatic upper airway segmentation and minimum cross-sectional area (CSAmin) localisation in two-dimensional (2D) radiographic airway images.

MATERIALS AND METHODS

Two hundred and one 2D airway images acquired using cone-beam computed tomography (CBCT) scanning were randomly assigned to a test group (n = 161) to train artificial intelligence (AI) models and a validation group (n = 40) to evaluate the accuracy of AI processing. Four AI models, UNet18, UNet36, DeepLab50 and DeepLab101, were trained to automatically segment the upper airway 2D images in the test group. Precision, recall, Intersection over Union, the dice similarity coefficient and size difference were used to evaluate the performance of the AI-driven segmentation models. The CSAmin height in each image was manually determined using three-dimensional CBCT data. The nonlinear mathematical morphology technique was used to calculate the CSAmin level. Height errors were assessed to evaluate the CSAmin localisation accuracy in the validation group. The time consumed for airway segmentation and CSAmin localisation was compared between manual and AI processing methods.

RESULTS

The precision of all four segmentation models exceeded 90.0%. No significant differences were found in the accuracy of any AI models. The consistency of CSAmin localisation in specific segments between manual and AI processing was 0.944. AI processing was much more efficient than manual processing in terms of airway segmentation and CSAmin localisation.

CONCLUSIONS

We successfully developed and validated a fully automatic AI-driven system for upper airway segmentation and CSAmin localisation using 2D radiographic airway images.

International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

MRI-based cephalometrics: a scoping review of current insights and future perspectives

OBJECTIVE

This review aims to explore the current status of magnetic resonance imaging (MRI) as a cephalometric tool, summarize the equipment design and methods, and propose recommendations for future research.

METHODS

A systematic search was conducted in electronic databases, including PubMed, Ovid MEDLINE, Scopus, Embase, Web of Science, EBSCOhost, LILACS, and Cochrane Library, using broad search terms. The articles published in any language till June 2022 were considered. Cephalometric studies conducted using the MRI dataset on human participants, phantom or cadaver were included. Two independent reviewers assessed the final eligible articles using the quality assessment score (QAS).

RESULTS

Nine studies were included in the final assessment. Studies used various methods, including 1.5 T or 3 T MRI systems and 3D or 2D MRI datasets. Among the imaging sequences, T1-weighted, T2-weighted and black bone MR images were used for cephalometric analysis. In addition, the reference standards varied among studies, such as traditional 2D cephalogram, cone-beam CT and phantom measurements. The mean QAS of all the included studies was 79% (± 14.4%). The main limitation of most studies was the small sample size and the heterogeneity of the methods, statistical tools used, and metric outcomes assessed.

CONCLUSIONS

Despite the heterogeneity and lack of metrological evidence on the effectiveness of MRI-based cephalometric analysis, the preliminary results demonstrated by in vivo and in vitro studies are encouraging. However, future studies exploring MRI sequences specific to cephalometric diagnosis are required for wider adoption of this technique in routine orthodontic practice.

Methodological parameters for upper airway assessment by cone-beam computed tomography in adults with obstructive sleep apnea: a systematic review of the literature and meta-analysis

BACKGROUND

A reliable method for analyzing the upper airway (UA) remains a challenge. This study aimed to report the methods for UA assessment using cone-beam computed tomography (CBCT) in adults with obstructive sleep apnea (OSA).

METHODS

We performed a systematic review (PROSPERO #CRD42021237490 and PRISMA checklist) that applied a search strategy to seven databases and grey literature.

RESULTS

In 29 studies with moderate-to-high risk of bias, investigators mostly reported the body position during CBCT (upright or supine) and hard tissue references, diverging in UA delimitation and terminologies. The meta-analysis showed two subgroups (upright and supine), and no statistical differences were identified (p = 0.18) considering the UA area. The volume in the OSA group was smaller than that in the control group (p < 0.003 and Cohen's d =  - 0.81) in the upright position. Patients with OSA showed smaller anteroposterior dimensions than the control group and were not affected by the position during image acquisition (p = 0.02; Cohen's d =  - 0.52). The lateral measurements were also lower in the OSA group (supine) (p = 0.002; Cohen's d =  - 0.6).

CONCLUSIONS

Patients with OSA showed smaller UA measurements in the upright (volume) and supine (lateral dimension) positions. The anteroposterior dimension was also reduced in patients with OSA compared to the control group, regardless of the position during CBCT acquisition.

Does Head and Neck Posture Affect Cone-Beam Computed Tomography Assessment of the Upper Airway?

PURPOSE

Radiographic analysis is often used as a screening tool to assess for risk of sleep-related breathing disorders. This study aimed to address 2 questions: (1) Does head posture significantly affect the minimum cross-sectional area (MCA)? and (2) Is the NBC3 (nasion-basion-C3) angle a reliable measurement to control for alteration of head position in cone-beam computed tomography (CBCT) scans?

METHODS

Study design: prospective cohort study.

SETTING

Private practices affiliated with a research institution.

PARTICIPANTS

convenience sample of adult volunteers.

VARIABLES

CBCT scans were taken in 2 conditions: baseline (natural head position, NHP) and 1 of 5 experimental conditions (head tilted up, head tilted down, sitting vs standing, use of chin-rest, and swallow variation). For the primary aim of our study, the primary predictor variable was head posture and the main outcome variable was percentage change in MCA. For the secondary aim, the primary predictor variable was head posture and the main outcome variable was degree change in NBC3 angle.

RESULTS

Ninety subjects were included (age 40.7 ± 13.7 years, 70% female). Mean NBC3 at baseline was 112.4 ± 8.3°. Head tilted down significantly decreased (-41.4 ± 18.5 mm², P = .03∗) and head tilted up significantly increased MCA (+147.4 ± 43.3 mm², P = .0018∗). Head tilted down significantly reduced the NBC3 angle measurement (-10.5 ± 6.8°, P = .006) and head tilted up significantly increased the NBC3 angle measurement (+14.4 ± 5.8°, P = .0004). A quadratic regression model was fitted with moderately strong correlation (R² = 0.54) showing an exponential effect of small changes in the NBC3 angle on MCA, P < .0001. The model predicts that increasing NBC3 by +5 and + 10° resulted in MCA changes of +25% and +88%, whereas a decrease in NBC3 by -5 and -10° results in MCA changes of -21% and -23%, respectively.

CONCLUSION

Alterations in head posture significantly affect the MCA of the upper airway on CBCT. The NBC3 angle can be used to reliably assess changes in cranio-cervical extension and validate comparisons of MCA between CBCT scans for the same patient. A standardized protocol for CBCT acquisition is proposed.

Hyoid bone position as an indicator of severe obstructive sleep apnea

BACKGROUND

The objective of this study was to evaluate the relationship between hyoid bone position and severity of obstructive sleep apnea (OSA), and to investigate its value as a complementary diagnostic method.

METHODS

A total of 133 patients who were diagnosed as OSA with an apnea-hypopnea index ≥ 5 were included. Clinical examination, level I polysomnography (PSG) and lateral cephalographic analysis were done. Comprehensive PSG characteristics were compared according to hyoid bone position and the predictive power of the distance between the mandible and hyoid was assessed.

RESULTS

The distance between the hyoid bone and mandibular plane was significantly longer in the severe OSA group (p = 0.013). The distance from hyoid bone to third vertebrae (C3) and hyoid bone to mentum were also longer in the severe OSA group but the difference did not reach statistical significance. The distance between hyoid bone and mandibular plane was effective in predicting severe OSA, with a cut-off value of 19.45 mm (AUC = 0.623, p = 0.040). When grouped according to a distance cut-off value of 19.45 mm, those with a longer distance between the hyoid bone and mandibular plane showed more respiratory disturbance, lower oxygen saturation levels, less deep slow wave sleep, and more fragmented sleep with arousals.

CONCLUSIONS

The distance between the hyoid bone and mandibular plane derived from cephalometric analysis can be a valuable diagnostic parameter that can be easily applied in differentiating severe OSA patients.

A Comparative Assessment of the Upper Pharyngeal Airway Dimensions among Different Anteroposterior Skeletal Patterns in 7–14-Year-Old Children: A Cephalometric Study

Background: The pharyngeal airway is a crucial part of the respiratory system’s function. Assessing the pharyngeal airway dimensions in different skeletal types is important in the orthodontic treatment of growing patients. The aim of this study was to compare the upper pharyngeal airway dimensions of 7–14-year-old children with different skeletal types. Methods: Three-hundred-sixty-one lateral cephalometric radiographs were grouped based on their skeletal patterns determined by the ANB angle as skeletal type I (n = 123), type II (n = 121), and type III (n = 117). The radiographs were divided into 4 groups: 7/8 YO (7–8 years old), 9/10 YO, 11/12 YO, and 13/14 YO. The cephalometric measurements comprised SNA, SNB, ANB, Ad1-PNS, Ad2-PNS, McUP, and McLP. An ANOVA was used to compare the group results. Results: Significant differences in Ad1-PNS, Ad2-PNS, McUP, and McLP in skeletal types II and III were found between age groups. Most upper pharyngeal airway dimensions in skeletal types II and III children were significantly wider in the 13/14 YO group than in the other age groups. Conclusion: The upper pharyngeal airway dimensions increased age-dependently in 7–14-year-old children, especially in skeletal types II and III. The upper pharyngeal airway dimensions could serve as a guide in differentiating the different skeletal classes in clinical settings.

Correlation between Polysomnographic Parameters and Tridimensional Changes in the Upper Airway of Obstructive Sleep Apnea Patients Treated with Mandibular Advancement Devices

BACKGROUND

The effectiveness of mandibular advancement devices has been solidly demonstrated in the past. They are considered a valid alternative treatment to continuous positive airway pressure for patients with obstructive sleep apnea. Nevertheless, the relationship between polysomnographic parameters and the increase in the volume of the upper airway in patients with obstructive sleep apnea syndrome has not been clearly established so far. This study aimed to determine the impact of these oral appliances upon the volume of the airway after the device titration phase and correlate it with the degree of mandibular advancement and the improvement of polysomnographic parameters.

METHODS

All patients were diagnosed by polysomnography and were treated with a customized, titratable mandibular advancement device. Three-dimensional volumetric measurements were performed using cone beam computed tomography.

RESULTS

The present study included 45 patients diagnosed with obstructive sleep apnea hypopnea syndrome (mild in 23 patients, moderate in 11 and severe in 11). Forty-four percent of the patients presented with an apnea hypopnea index <5/h at the end of treatment. The volume of the upper airway increased an average of 4.3 ± 5.9 cm3, this represents a percentage increase of 20.9%, which was significantly correlated with an apnea hypopnea index and a minimum oxygen saturation improvement.

CONCLUSIONS

The mandibular advancement device used was found to be effective in improving polysomnographic parameters. Moreover, the oral appliance was able to significantly increase the tridimensional dimensions of the upper airway. Moreover, this finding was correlated with a reduction in the apnea hypopnea index (p = 0.007) and an increase on minimum oxygen saturation (p = 0.033).

Elevated Hyoid Bone Position in Response to Mandibular Advancing Appliance Predicts Effectiveness of the Appliance for Obstructive Sleep Apnea

The objective was to determine whether hyoid bone elevation induced by an anterior mandibular positioning appliance (AMP) predicts the effectiveness of the AMP in patients with obstructive sleep apnea (OSA). Fifteen patients (12 males and 3 females) underwent polysomnographic recordings and lateral cephalograms before and after AMP use of at least 6 months. Measurements of sleep variables and upper airway morphology were compared between pre-AMP and with-AMP states. The AMP appliance reduced apnea-hypopnea indices (AHI) ~53% (33.77 ± 3.29 vs. 15.85 ± 3.78, P = 0.0013). Cephalograms of the oropharyngeal airway showed that the hyoid bone moved superiorly toward the inferior mandibular border (Δ H-MP) ~5 mm (23.4 ± 1.44 vs. 18.27 ± 1.86, P = 0.0377), with the AMP inserted in the oral cavity; no airway measurement other than hyoid bone position changed. No significant correlations emerged between AHI improvement (Δ AHI) and amounts of hyoid elevation (Δ H-MP) when all patients were pooled. However, when the samples were subcategorized, the correlation coefficients increased significantly (P &lt; 0.01) in both subgroups. This outcome suggests the presence of two distinct types among the “Good-Responders” to AMP appliance use. Overall use of the AMP appliance is effective; however, the effectiveness of the appliance appears to depend on the mode of hyoid elevations, likely resulting from muscle responsiveness in patients with AMP use. The results suggest that Δ H-MP measurements may be a useful marker to segregate patients with tongue and hyoid muscles responsive to AMP from those not-so-responsive.

Cone beam computed tomographic evaluation of pharyngeal airway in North Indian children with different skeletal patterns

BACKGROUND

In growing patients with skeletal discrepancies, early assessment of functional factors can be vital for the restoration of normal craniofacial growth.

AIM

To compare airway volumes in patients with mandibular retrognathism with the normal anteroposterior skeletal relationship, thereby assessing the association between cephalometric variables and airway morphology.

METHODS

Cone-beam computed tomography volume scans, and lateral cephalograms, 3-dimensional airway volume and cross-sectional areas of 120 healthy children (54 boys and 66 girls mean age 15.19 ± 1.28) which were done for orthodontic assessment were evaluated. The subjects were divided into 2 groups based on the angle formed between point A, Nasion and point B (ANB) values and cephalometric variables (such as anterior and posterior facial height, gonial angle etc.) airway volumes, and cross-sectional measurements were compared using independent t tests. Pearson’s correlation coefficient test was used to detect any relationship of different parts of the airway and between airway volume and 2-dimensional cephalometric variables.

RESULTS

Means and standard deviations for cephalometric, cross-sectional, and volumetric variables were compared. ANB, mandibular body length and facial convexity were statistically highly significant (P < 0.01) whereas condylion to point A, nasal airway and total airway volume (P < 0.05) were statistically significant. The nasal airway volume and the superior pharyngeal airway volume had a positive correlation (P < 0.01), nasal airway was correlated to middle (P < 0.05) and total airway superior had a relation with middle (P < 0.05), inferior and total airway (P < 0.05), middle was related to all other airways; inferior was also related to all the airways except nasal. Lateral cephalometric values were positively correlated with the airway volume with Frankfurt Mandibular Plane Angle and facial convexity showed significant correlations with total airway volume (P < 0.05). Additionally, ANB angle was significantly correlated with total airway volume and superior airway (P < 0.05).

CONCLUSION

The mean total airway volume in patients with retrognathic mandible was significantly smaller than that of patients with a normal mandible.

Orthopedic Treatment for Class II Malocclusion with Functional Appliances and Its Effect on Upper Airways: A Systematic Review with Meta-Analysis

Aim of this systematic review was to assess the effects of orthopedic treatment for Class II malocclusion with Functional Appliances (FAs) on the dimensions of the upper airways. Eight databases were searched up to October 2020 for randomized or nonrandomized clinical studies on FA treatment of Class II patients with untreated control groups. After duplicate study selection, data extraction, and risk of bias assessment according to Cochrane guidelines, random effects meta-analyses of mean differences (MDs) and their 95% confidence intervals (CIs) were performed, followed by subgroup/meta-regression analyses and assessment of the quality of evidence. A total of 20 nonrandomized clinical studies (4 prospective/16 retrospective) including 969 patients (47.9% male; mean age 10.9 years) were identified. Orthopedic treatment with FAs was associated with increased oropharynx volume (MD = 2356.14 mm³; 95% CI = 1276.36 to 3435.92 mm³; p < 0.001) compared to natural growth. Additionally, significant increases in nasopharynx volume, minimal constricted axial area of pharyngeal airway, and airway were seen, while removable FAs showed considerably greater effects than fixed FAs (p = 0.04). Finally, patient age and treatment duration had a significant influence in the effect of FAs on airways, as had baseline matching and sample size adequacy. Clinical evidence on orthopedic Class II treatment with FAs is associated with increased upper airway dimensions. However, the quality of evidence is very low due to methodological issues of existing studies, while the clinical relevance of increases in airway dimensions remains unclear.

Screening of obstructive sleep apnea (OSA) risk in adolescent population and study of association with craniofacial and upper airway morphology

Background

Obstructive sleep apnea (OSA) is a common form of sleep-disordered breathing with high prevalence and associated co-morbidities. It still goes largely under-reported due to events occurring in sleep and difficulty in identifying predisposing factors.

Aims

To perform questionnaire-based screening of OSA-risk in adolescents and study association of OSA-risk with craniofacial and upper airway morphology.

Material and methods

Modified STOP-BANG questionnaire was used for screening OSA-risk in adolescent orthodontic patients (10-19 years) in a government dental hospital in India. Patients were categorised into two groups: OSA-risk and non-risk, based on the questionnaire scores, and were subsequently evaluated for craniofacial and upper airway morphology, both on examination and on lateral cephalometric radiographs.

Results

Documented a high prevalence of 14% for OSA-risk in adolescent orthodontic patients. The extra-oral and intra-oral parameters found significantly associated with OSA-risk were convex profile [Odd's ratio (OR) - 3.824], steep mandibular plane angle [MPA] (OR- 79.75), Type 3/4 faucial pillars (OR- 11.227), Class II molar relationship (OR - 4.518), ovoid upper arch form (OR - 13.750). In addition, the cephalometric parameters: ANB (p- 0.025), SN-MP (p- 0.007), BA-SN (p- 0.020), PNS-AD1 (p < 0.001), PNS-AD2 (p - 0.001) also showed highly significant association to OSA-risk. The ROC curves demonstrated high sensitivity and specificity for PNS-AD1 (60%,83.3%), PNS-AD2 (73.3%, 70%) and SN-MP (60%,70%), respectively for OSA-risk.

Conclusions

The study supported applicability of modified STOP-BANG questionnaire for OSA-risk in Indian adolescents. The parameters [extra-oral, intra-oral, cephalometric and upper airway (PNS-AD1, PNS-AD2, SN-MP)] significantly associated with OSA-risk, were identified.