A cephalometric and electromyographic study of upper airway structures in the upright and supine positions

Difference in the Electromyographic Behavior of the Masticatory and Swallowing Muscles During Cued Versus Spontaneous Swallowing

The risk of dysphagia and/or aspiration is determined using screening tests, such as the repeated saliva swallowing test and modified water swallowing test, which evaluate cued swallowing. However, humans masticate and swallow foods with various consistencies, forms, and amounts, without conscious awareness. Therefore, this study aimed to examine the difference in the behavior of masticatory and swallowing muscles during spontaneous versus cued swallowing through a series of mastication and swallowing processes by evaluating surface electromyogram (sEMG) signals. The effect of the consistency and amount of food on the behavior of these muscles was also investigated. The sEMG recordings of the masseter muscles and anterior belly of the digastric muscle for 12 subjects, and genioglossus muscle for 5 subjects were obtained. The genioglossus activity was recorded using custom-made ball electrodes. The test foods were cookies and tofu, in amounts of 2 g and 4 g. The normalized muscle activity (integrated EMG), duration of the muscle activity, initial activation timepoint of each muscle, and total duration of swallowing were compared among four conditions. The activity of each muscle was significantly higher during the swallowing of cookies than tofu, for 4 g vs 2 g, and for cued versus spontaneous swallowing. The duration of each muscle activity, initial activation timepoint, and total duration of swallowing were significantly longer for cookies versus tofu, for 4 g vs 2 g, and for spontaneous versus cued swallowing. These results suggest that the behavior of the masticatory and swallowing muscles is affected by cued swallowing and by the consistency and amount of food.

Skeletal and Dentoalveolar Changes in Growing Patients Treated with Rapid Maxillary Expansion Measured in 3D Cone-Beam Computed Tomography

The skeletal and dental effects of rapid maxillary expansion (RME) have been extensively studied, but high-quality research is still needed to determine the three-dimensional (3D) effects of RME. The aim of this study was to compare skeletal and dentoalveolar parameters through cone-beam computed tomography (CBCT) pre- (T1) and post-treatment (T2) with respect to RME. Twenty growing patients (mean age 10.7 years) were treated with a Hyrax-type expander. A 3D CBCT was performed at T1 and T2, measuring nasal width, maxillary width, palatal height, maxillary arch perimeter, angulation of the upper first molar, and intermolar width. The mean palatal suture opening was 2.85 ± 0.62 mm (p < 0.0001). Nasal width increased 1.28 ± 0.64 mm and maxillary width 2.79 ± 1.48 mm (p < 0.0001). In contrast, palatal height was reduced 0.65 ± 0.64 mm (p < 0.0001). Regarding arch perimeter, the radicular perimeter increased 2.89 ± 1.80 mm, while the coronal perimeter increased 3.42 ± 2.09 mm (p < 0.0001). Molar angulation increased 5.62 ± 3.20° for the right molar and 4.74 ± 2.22° for the left molar (p < 0.0001). Intermolar width increased 5.21 ± 1.55 mm (p < 0.0001). Treatment with Hyrax produced a significant opening in the mean palatal suture. Also, a significant increase in nasal width, maxillary width, arch perimeter, molar angulation, and intermolar width, and a decrease in palatal height, were observed.

The relationship between aerodynamic characteristics of the upper airway and severity of obstructive sleep apnea in adults

OBJECTIVE

To investigate the relationship between aerodynamic characteristics of the upper airway and severity of obstructive sleep apnea (OSA) in adults.

METHODS

Ninety-seven adult OSA patients underwent polysomnography and cone beam computed tomography (CBCT). The anatomical and aerodynamic characteristics were measured based on CBCT images and computational fluid dynamics modelling of the upper airway.

RESULTS

After controlling for patients' gender, age, and body mass index (BMI), the maximum velocity during inspiration (In-Vmax) led to the largest increase in the explanatory power of apnea-hypopnea index (AHI) variation. The In-Vmax was closely correlated with the minimum axial area, and their relationship was represented by an inversely proportional fitted curve.

CONCLUSIONS

The In-Vmax was the most relevant to OSA severity, and it could be used to assist in recognizing severe OSA patients and as a primary variable to evaluate treatment outcomes of OSA. The In-Vmax was closely related to the most constricted area of the upper airway.

Three-dimensional evaluation of the association between tongue position and upper airway morphology in adults: A cross-sectional study

Objective

This study aimed to evaluate the association between low tongue position (LTP) and the volume and dimensions of the nasopharyngeal, retropalatal, retroglossal, and hypopharyngeal segments of the upper airway.

Methods

A total of 194 subjects, including 91 males and 103 females were divided into a resting tongue position (RTP) group and a LTP group according to their tongue position. Subjects in the LTP group were divided into four subgroups (Q1, Q2, Q3, and Q4) according to the intraoral space volume. The 3D slicer software was used to measure the volume and minimum and average cross-sectional areas of each group. Airway differences between the RTP and LTP groups were analyzed to explore the association between tongue position and the upper airway.

Results

No significant differences were found in the airway dimensions between the RTP and LTP groups. For both retropalatal and retroglossal segments, the volume and average cross-sectional area were significantly greater in the patients with extremely low tongue position. Regression analysis showed that the retroglossal airway dimensions were positively correlated with the intraoral space volume and negatively correlated with A point-nasion-B point and palatal plane to mandibular plane. Males generally had larger retroglossal and hypopharyngeal airways than females.

Conclusions

Tongue position did not significantly influence upper airway volume or dimensions, except in the extremely LTP subgroup.

Heritability of cephalometric variables of airway morphology in twins with completed active growth

BACKGROUND

The interplay between genetic and environmental impacts on dental and facial morphology has been widely analyzed, but little is known about their relative contributions to airway morphology. The aim of this study was to evaluate the genetic and environmental influences on the cephalometric variables of airway morphology in a group of postpubertal twins with completed craniofacial growth.

MATERIALS AND METHODS

The materials comprised lateral head cephalograms of 94 pairs of twins (50 monozygotic, 44 dizygotic) with completed craniofacial growth. Zygosity was determined using 15 specific DNA markers. The computerized cephalometric analysis included 22 craniofacial, hyoideal, pharyngeal structural linear and angular variables. Genetic analysis and heritability estimation were performed using maximum likelihood genetic structural equation modeling (GSEM). Principal component analysis (PCA) was used to assess the correlations between cephalometric measurement variables.

RESULTS

Upper airway dimensions showed moderate to high genetic determination (SPPW-SPP and U-MPW: a² = 0.64 and 0.5, respectively). Lower airway parameters showed only common and specific environmental determination (PPW-TPP a² = 0.24, e² = 0.38; LPW-V c² = 0.2, e² = 0.63; PCV-AH c² = 0.47, e² = 0.28). The relationship between the maxilla and the hyoid bone (for variables PNS-AH, ANS-AH d² = 0.9, 0.92, respectively) showed very strong additive genetic determination. The size of the soft palate was affected by additive and dominant genes. Its length (SPL) was strongly influenced by dominant genes, while its width (SPW) showed a moderate additive genetic influence. Owing to correlations in the behavior of variables, the data could be expressed in 5 principal components that jointly explained 36.8% of the total variance.

CONCLUSIONS

The dimensions of the upper airway are strongly determined by genes, while the parameters of the lower airway depend mainly on environmental factors.

TRIAL REGISTRATION

The protocol has been approved by the Kaunas Regional Ethical Committee (No. BE - 2-41., May 13, 2020).

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.

Dimensional changes of upper airway after slow vs rapid miniscrew-supported maxillary expansion in adolescents: a cone-beam computed tomography study

BACKGROUND

To date, the effects of different activation rates of miniscrew-supported expanders on the airway have not been compared. Hence, the purpose of this retrospective study was to evaluate and compare the effects of slow and rapid miniscrew-supported maxillary expansion on the upper airway dimensions using cone-beam computed tomography (CBCT).

METHODS

Data of 20 patients (Age 12 to 16 years old) treated using miniscrew-supported expanders at the Faculty of Dentistry, Alexandria University was collected. The patients were equally divided into two groups according to the activation protocol; slow maxillary expansion (SME): activation once every other day, and rapid maxillary expansion (RME): activation twice daily. CBCT scans obtained pre-expansion and 5 months post-expansion were used to evaluate the changes in the upper airway dimensions. Comparisons between the two time points within each group were done using paired samples t-test. SME and RME groups were compared using independent samples t-test. Significance level was set at p < 0.05.

RESULTS

Both groups showed a significant increase in anterior, middle, and posterior nasal cavity width. SME resulted in significantly greater increase of the anterior nasal cavity width than RME (Mean difference between the groups, 2.64 mm; 95% CI, 0.83, 4.45; p = 0.007). The dimensions of the retropalatal and retroglossal airways did not change significantly in either group. Both groups resulted in a significant increase of maxillary width, palatal width, and inter-molar width. RME showed a significantly larger increase of inter-molar width than SME (Mean difference between the groups, - 2.44 mm; 95% CI, - 3.88, - 1.00; p = 0.002).

CONCLUSIONS

The use of either a slow or rapid activation protocol is effective in expanding the nasomaxillary complex, with greater expansion achieved in the anterior section of the nasal cavity using the slow rate. However, the expander design employed in the current study does not affect the dimensions of the retropalatal or retroglossal airways.

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.

The Efficacy of Twin-Block Appliances for the Treatment of Obstructive Sleep Apnea in Children: A Systematic Review and Meta-Analysis

Objective

To evaluate the efficacy of twin-block appliance in the treatment of children with obstructive sleep apnea (OSA).

Methods

Two independent reviewers conducted a systematic review of seven databases from database establishment until October 16, 2021. There were no language restrictions. The outcomes were changes in apnea-hypopnea index (AHI), oxyhemoglobin desaturation index (ODI), and lowest arterial oxygen saturation (lowest SaO2). National Institute for Health and Clinical Excellence (NICE) tool was used to assess the quality of the studies included.

Results

A total of 207 articles were screened for relevance, and 6 of them met the inclusion criteria for our meta-analysis. Four of the studies were case series, 1 was nonrandomized control trial, and 1 was a randomized crossover clinical trial. After twin-block therapy, there was a significant decrease in AHI (4.35 events/hour, 95% CI: 4.04, 4.66, p ≤ 0.001). The lowest SaO2 significantly increased by 9.17% (95% CI: 12.05, 6.28, p ≤ 0.001). Sensitivity analysis by excluding studies one by one showed stable and favorable results in lowest SaO2 and AHI.

Conclusions

Results from the meta-analysis showed that the use of twin-block appliance significantly decreased AHI and significantly increased lowest SaO2. Hence, twin-block appliance therapy may be an effective method for the treatment of pediatric OSA. Further large sample size randomized controlled trials are needed to assess this treatment efficacy in children with obstructive sleep apnea.

At-Home Orthodontic Treatment for Severe Teeth Arch Malalignment and Severe Obstructive Sleep Apnea Syndrome in a Child with Cerebral Palsy

Children with cerebral palsy typically have severe teeth arch malalignment, causing swallowing and respiration dysfunction. Malalignment in cerebral palsy, especially in children, worsens dysphagia and respiratory disorders; sometimes, it is also noted with obstructive sleep apnea. However, no study has reported on the improvement in obstructive sleep apnea after at-home orthodontic treatment in children with cerebral palsy. We herein present a pediatric case of cerebral palsy wherein obstructive sleep apnea improved with at-home orthodontic treatment for malalignment. We administered at-home orthodontic treatment to a 15-year-old boy with quadriplegia, due to spastic-type cerebral palsy, having no oral intake, obstructive sleep apnea, and teeth arch malalignment. After treatment, a decline in the severity of sleep apnea was observed. Perioral muscle hypertension and oral intake difficulties cause maxillary protrusion, narrowed teeth arch, and tilting of teeth in children with cerebral palsy. We expanded the oral cavity volume by orthodontic treatment to relieve muscle hypertension and correct the tongue position, thereby remarkably improving obstructive sleep apnea. Our findings suggest that at-home orthodontic treatment for malalignment effectively improves perioral muscle hypertension, glossoptosis, and obstructive sleep apnea.

Relationship between Dental Occlusion and Maximum Tongue Pressure in Preschool Children Aged 4-6 Years

Tongue function is regarded as a primary factor in the etiology of malocclusion, but details of the relationship remain unknown. The purpose of the present study was to investigate maximum tongue pressure, in preschool children to examine its relationship with dental occlusion. A total of 477 healthy children (248 boys, 229 girls, aged 4-6 years) were recruited. Dental occlusion was assessed visually to record sagittal, vertical, and transverse malocclusion, and space discrepancies. Maximum tongue pressure was measured using a balloon-based tongue pressure measurement device. Additionally, 72 children (37 boys, 35 girls, aged 4-5 years) were recruited for a 1-year follow-up study. Approximately half of the children (53.5%) showed some type of malocclusion in the present study. Maximum tongue pressure was highest in the 6-year-old children. The results of a two-way ANCOVA show that the effect of age was significant (p < 0.001); however, the effects of sex and dental occlusion, or the interactions among these variables, did not reach significance. Additionally, maximum tongue pressure increased significantly in the 1-year follow-up study (p < 0.001), especially in the normal occlusion group. Maximum tongue pressure increases markedly with growth in the preschool years and can be associated with some types of malocclusion in preschool children.

Characteristics of airway resistance in obstructive sleep apnea patients with asthma on oscillometry

BACKGROUND

Asthma and obstructive sleep apnea (OSA) are prevalent chronic respiratory disorders with a high tendency to coexist. Both diseases involve increased airway resistance in the upright position because of narrow upper or lower airways. Moreover, there is a marked increase in airway resistance in the supine position in patients with OSA. We verified the characteristics of OSA in combination with asthma.

METHODS

Airway resistance was measured by oscillometry in the upright and supine position in 11 healthy participants (control), 59 patients with OSA alone, and 33 OSA patients with asthma (coexistence) in the hospital between April 2014 and July 2020. We compared the differences in airway resistance between the upright and supine positions among the three groups. In addition, we performed cephalometry to evaluate the upper airway structure in patients with OSA alone and in patients with both OSA and asthma.

RESULTS

A marked increase in airway resistance due to postural change was observed in the "OSA alone" group compared to that in the control group. However, this was not observed in the "coexistence" and control groups. Moreover, the "coexistence" group had fewer structural abnormalities in the upper airway than the "OSA alone" group on cephalometry.

CONCLUSIONS

The airway resistance of patients with OSA alone markedly increased with posture change because of upper airway abnormalities. However, there was a smaller increase with postural changes in OSA patients with asthma, suggesting the possibility of a smaller degree of upper airway abnormality compared to patients with OSA alone.

CLINICAL TRIAL REGISTRATION NUMBER

This study is approved by the research ethics committee of the Shinshu University School of Medicine (permission number: 4272).

Predicting the presence and severity of obstructive sleep apnea based on mandibular measurements using quantitative analysis of facial profiles via three-dimensional photogrammetry

BACKGROUND

In obstructive sleep apnea (OSA), the upper airway is obstructed during sleep due to obesity and/or posterior collapse of the tongue root. Maxillofacial morphological abnormalities increase the risk of OSA in the Asian population. This study sought to elucidate whether three-dimensional (3D) photogrammetry measurements correlate with the severity of OSA irrespective of sex and degree of obesity.

METHODS

A prospective pilot study was performed, in which 37 consecutive adult patients (M/F = 28/9) underwent polysomnography and 3D photogrammetry in the supine position for the diagnosis of OSA. Measurements obtained from 3D photogrammetry included mandibular width (Mw), mandibular length (Ml), mandibular depth (Md), mandibular width-length angle (Mwla), and mandibular area (Ma). The effects of sex and body mass index (BMI) on the measurements and their association with the apnea-hypopnea index (AHI) were statistically analyzed. The inter-rater reliability of the measurements was evaluated using intraclass correlation coefficients (ICC).

RESULTS

Mwla (R = 0.73, p < 0.01), Mw (R = 0.39, p < 0.05), and Md (R = -0.34, p < 0.05) were significantly correlated with the severity of OSA. On multivariate analysis, Mwla (p < 0.01) and Md (p < 0.05) remained independent factors for AHI after adjusting for sex, age, BMI, and neck circumference. In addition, diagnosability analysis revealed that Mwla was useful for identifying the presence of OSA (AHI ≥5) (cutoff: 78.6°, sensitivity: 0.938, specificity: 0.800, area under the curve: 0.931). The ICC was >0.9, showing high reliability.

CONCLUSIONS

This study suggests that Mwla measured using 3D photogrammetry can predict the presence of OSA and correlates with the severity of OSA, independent of obesity and sex.

A computational model of upper airway respiratory function with muscular coupling

A two dimensional finite element model of upper airway respiratory function was developed emphasizing the effects of dilator muscular activation on the human retro-lingual airway. The model utilized an upright mid-sagittal computed tomography of the human head and neck to reconstruct relevant structures of the tongue, mandible, and the hyoid-related soft tissues, along with the retro-lingual airway. The reconstructed geometry was divided into fluid and solid domains and discretized into finite element (FE) meshes used for the computational model. Three cases were investigated: standing position; supine position; and supine position coupled with dilator muscle activation. Computations were performed for the inspiration stage of the breathing cycle, utilizing a fluid-structure interaction (FSI) method to couple structural deformation with airflow dynamics. The spatio-temporal deformation of the structures surrounding the airway wall were predicted to be in general agreement with known changes from upright to supine posture on luminal opening, as well as the distribution of airflow. The model effectively captured the effects of muscular stimulation on the upper airway anatomical changes, the flow characteristics relevant to airway reduction in the supine position and airway enlargement with muscle activation. The smallest airway opening in the retro-lingual section is predicted to occur at the epiglottic region in all the three cases considered, an unexpected vulnerable location of airway obstruction. The model also predicted that hyoid displacement would be associated with recovery from airway collapse. This information may be useful for building more complex models relevant to mechanisms and clinical interventions for obstructive sleep apnea.

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

Purpose

The aim of this study was to determine changes in the tongue area and pharyngeal airway space (PAS) after intraoral vertical ramus osteotomy (IVRO).

Materials and Methods

Serial lateral cephalograms of 40 patients with mandibular prognathism who underwent IVRO were evaluated before (T1), immediately after (T2), and more than 1 year after (T3) surgery. Paired t-tests and Pearson's correlation analysis were used to evaluate the postoperative changes in the mandible, nasopharyngeal airway (NOP), retropalatal pharyngeal airway (RPP), retroglossal pharyngeal airway (RGP), hypopharyngeal airway (HOP), PAS, and tongue area (TA). The null hypothesis states that there are no significant correlations among the extent of mandibular setback and the changes in the TA and PAS after IVRO.

Results

Immediately after the operation (T12), the mandible was set back by 12.6 mm. The NOP, HOP, and PAS were significantly reduced by 35.7 mm², 116 mm², and 185 mm², respectively. The TA was increased by 69.6 mm². The changes in PAS and TA revealed no significant difference between female and male patients at T12, T23, and T13. Moreover, no significant correlations were found among the extent of mandibular setback, TA changes, and PAS changes after IVRO. Thus, the null hypothesis was accepted.

Conclusions

At the final follow-up (T13), no significant change was found in the PAS (including NOP, RPP, RGP, and HOP) and TA. The changes in PAS and TA revealed no significant difference between female and male patients at T12, T23, and T13.

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.

The risk assessment by clinical background and cephalometry for obstructive sleep apnea with CPAP indication in Japanese

Obstructive sleep apnea (OSA) is a disease characterized by a brief period of cessation or marked decline in ventilation. The standard treatment is continuous positive airway pressure (CPAP). To determine the indication, full-night polysomnography (PSG) is required; however, it is a stressful examination. We verified the usefulness of pulse-oximetry at home as a predictor for CPAP indication before PSG. Simultaneously, the clinical background and cephalometry were also verified. Among 376 subjects who received PSG at our hospital from February 2005 to April 2020, 138 subjects received pulse-oximetry at home before PSG were enrolled retrospectively and performed logistic regression analysis on those with CPAP indication. Concurrently, 262 of 376 subjects received cephalometry were enrolled, and logistic regression analysis were performed using clinical background and cephalometry. A 3% oxygen desaturation (3% ODI) on the pulse-oximeter was a predictor for CPAP indication. The positive predictive value of 3% ODI ≥ 28.5 events/h was 73.3% and the negative predictive value was 62.5%. Older age, higher body mass index (BMI), stronger lower jaw retraction (wider ∠ANB), and longer distance from the anterior superior tip of the hyoid bone to the mandibular plane (MP-H) on cephalometry were also independent predictors. The positive predictive value when both BMI ≥ 26.0 kg/m2 and MP-H ≥ 17.5 mm were present was 88.2% and the negative predictive value when both were absent was 71.3%. The combination of clinical background and cephalometry would be a useful screening tool as well as a pulse-oximetry at home for CPAP indication.

Effect of back-up head-elevated position during drug-induced sleep endoscopy in obstructive sleep apnea patients

PURPOSE

This study aimed to evaluate the difference of upper airway collapse between the back-up head-elevated position (a 45° upward inclination) and supine position to better elucidate the role of back-up head-elevated position in reductions of obstructive sleep apnea (OSA) severity.

METHODS

From August 2016 to May 2019, 198 patients aged between 18 and 70 years were recruited in this study prospectively. Drug-induced sleep endoscopy (DISE) findings were recorded with the patients first placed in the supine position then into the back-up head-elevated position with a 45° upward inclination.

RESULTS

From the supine to back-up head-elevated position, a significant decrease in the severity of collapse was observed in velum anteroposterior collapse and velum concentric collapse (p < 0.001 and p < 0.001, respectively), which was more predominant in patients with mild OSA than in patients with moderate to severe OSA. On the other hand, there was no significant improvement of any other collapse at the level of oropharynx, tongue base, or epiglottis when the position was shifted from the supine into back-up head-elevated position.

CONCLUSIONS

The back-up head-elevated position with a 45° upward inclination improved upper airway obstruction during DISE in velum anteroposterior collapse and velum concentric collapse. The proportion of patients with amelioration of upper airway collapse was much higher in patients with mild OSA than in patients with moderate to severe OSA. The back-up head-elevated position may be a reasonable alternative to traditional positional therapy for certain subgroups of patients with OSA.

Changes in pharyngeal airway dimensions following incremental and maximum bite advancement during Herbst-rapid palatal expander appliance therapy in late adolescent and young adult patients: a randomized non-controlled prospective clinical study

OBJECTIVES

This was a parallel, assessor-blinded, randomized, non-controlled prospective trial with the objective to evaluate and compare the effects of maximum advancement (MA) and incremental advancement (IA) of mandible with cast-splint-type Herbst-rapid palatal expander (RPE) appliance on pharyngeal airway dimensions and hyoid bone position in skeletal Class II late adolescents and young adults.

MATERIALS AND METHODS

A total of 48 patients (19 male and 29 female, mean age: 15.45 ± 1.42 years) with skeletal Class II malocclusion were treated with cast-splint Herbst-RPE appliance. Inclusion criteria were skeletal Class II malocclusion, mandibular retrognathia, bilateral Class II molar and canine relationship, increased overjet, normal or decreased vertical dimensions, minimal crowding, and no missing teeth. Enrolled subjects were randomly allocated into two groups according to mandibular advancement type: IA and MA Herbst-RPE therapy. The outcome assessor was blinded. Advancement in MA group was adjusted until tête-à-tête incisor relationship or super Class I molar relationship was obtained. Initial forward movement in IA group was 4-5 mm and followed by bimonthly 2 mm of subsequent advancements. Skeletal, pharyngeal airway, and hyoid measurements were performed using lateral cephalometric films. Statistical significance was set at P value of less than 0.05.

RESULTS

Hypopharyngeal airway dimensions (P < 0.000), oropharyngeal airway dimensions (P < 0.001, P < 0.007), and PASmin values (P < 0.010, P < 0.009) were increased and soft palate angle (P < 0.018, P < 0.007) was decreased in MA and IA groups significantly. Hyoid bone measurements revealed a significant difference in H-Cv2 distance (MA: P < 0.002-P < 0.002; IA: P < 0.001-P < 0.043) and H-Cv3 distance (P < 0.005, P < 0.001) for both groups. However, all these changes did not differ among the MA and IA activation groups. ANB°, Wits, overjet, and overbite measurements decreased and SNB°, Co-Gn, Na-Me, ANS-Me, and S-Go increased with the treatment significantly in both mandibular advancement groups (P < 0.000-P < 0.040).

CONCLUSIONS

Herbst-RPE appliance provided a similar improvement in the oropharyngeal and hypopharyngeal airway dimensions and similar changes in sagittal and vertical hyoid position for both maximum and IA protocols in patients with skeletal Class II malocclusion.

TRIAL REGISTRATION

ISRCTN69743543.

Genioglossus motor unit activity in supine and upright postures in obstructive sleep apnea

This study investigated whether a change in posture affected the activity of the upper-airway dilator muscle genioglossus in participants with and without obstructive sleep apnea (OSA). During wakefulness, a monopolar needle electrode was used to record single motor unit activity in genioglossus in supine and upright positions to alter the gravitational load that causes narrowing of the upper airway. Activity from 472 motor units was recorded during quiet breathing in 17 males, nine of whom had OSA. The mean number of motor units for each participant was 11.8 (SD 3.4) in the upright and 16.0 (SD 4.2) in the supine posture. For respiratory-modulated motor units, there were no significant differences in discharge frequencies between healthy controls and participants with OSA. Within each breath, genioglossus activity increased through the recruitment of phasic motor units and an increase in firing rate, with an overall increase of ~6 Hz (50%) across both postures and participant groups. However, the supine posture did not lead to compensatory increases in the peak discharge frequencies of inspiratory and expiratory motor units, despite the increase in gravitational load on the upper airway. Posture also had no significant effect on the discharge frequency of motor units that showed no respiratory modulation during quiet breathing. We postulate that, in wakefulness, any increase in genioglossus activity to compensate for the gravitational effects on the upper airway is achieved primarily through the recruitment of additional motor units in both healthy controls and participants with OSA.

Relationship between cephalometric parameters and the apnoea-hypopnoea index in OSA patients: a retrospective cohort study

OBJECTIVE

The purpose of this study was to assess the relationship between cephalometric parameters and apnoea-hypopnoea index (AHI) controlling for the effect of gender, age, and body mass index (BMI) on a large sample of patients with obstructive sleep apnoea (OSA).

METHODS

This retrospective cohort study was conducted on the lateral cephalograms of 253 Caucasian adult OSA patients. Cephalometric analyses were performed using 14 parameters for skeletal and soft tissue morphology, including antero-posterior and vertical jaw relationships, hyoid bone position, soft palate length and thickness, airway space, and tongue length and height. A hierarchical regression was run to examine the amount of variability in AHI that cephalometric variables explained after controlling for patients' general characteristics (gender, age, and BMI).

RESULTS

After controlling for gender, age, and BMI, the increase in AHI variance accounted for by cephalometric parameters was equal to 0.103. Among the cephalometric variables, only MP-H and PNS-P were statistically significant (P < 0.05).

LIMITATIONS

Given the retrospective nature of the study, it is difficult to assess whether other confounding variables not considered in the present study could have influenced the relationship between cephalometric parameters and AHI.

CONCLUSIONS

This study revealed the existence of a relationship between OSA severity and some cephalometric parameters. Indeed soft palate length and vertical position of the hyoid bone were significant predictors of AHI in adult Caucasian OSA patients.

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.

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

Background/Purpose

Obstructive sleep apnea syndrome (OSAS) is a common form of sleep disorder. Lateral cephalograms and cone-beam computed tomography (CBCT) have been used for evaluation. However, it is lack of position comparison for these two assessments. Therefore, this study was aimed to evaluate the difference of upper airway measurements taken from lateral cephalograms in upright position and CBCT in supine position.

Material and methods

This retrospective study enrolled patients with lateral cephalograms and CBCT images due to diagnostic necessity. The anterior-posterior distance of most constricted area in pharynx (PASmin) and the distance from mandibular plane to hyoid bone (MP-H) were identified and measured from 21 normal subjects without obstructive sleep apnea (9 males and 12 females, mean age 21.2 years). A paired data were measured from lateral cephalograms taken in upright position and lateral cephalometric images derived from CBCT taken in supine position. Both images were taken within two months. All data were analyzed statistically.

Results

No significant difference was identified in intra-examiner reliability (P > 0.05). PASmin measured from lateral cephalograms in upright position was larger than that taken from CBCT derived cephalometric images, but without statistical significant difference (P = 0.073). Significant difference of MP-H length was identified between two different image taking methods (P = 0.000), and the measurement was significantly larger in cephalograms taken from upright position. No correlations were found among the variables (Body Mass Index (BMI), age, gender) in this study. The only two variables correlated were PASmin and MP-H, and they were negatively correlated (r = −0.535).

Conclusion

The anterior-posterior distance of most constricted area in pharynx (PASmin) and distance of mandibular plane to hyoid bone (MP-H) can be influenced due to change of body position.

Are computed tomography 3D measurements of the upper airways in mouth-breathing children in agreement with the ENT clinical diagnosis of obstruction?

Introduction

Imaging studies have hystorically been used to support the clinical otorhinolaryngological evaluation of the upper respiratory tract for the diagnosis of obstructive causes of oral breathing.

Objective

The objective of this study was to compare 3D volumetric measurements of nasal cavity, nasopharynx and oropharynx of obstructed mouth-breathing children with measurements of non-obstructed mouth-breathing children.

Methods

This retrospective study included 25 mouth-breathing children aged 5–9 years evaluated by otorhinolaryngological clinical examination, flexible nasoendoscopy and full-head multi-slice computed tomography. Tomographic volumetric measurements and dichotomic otorhinolaryngological diagnosis (obstructed vs. non-obstructed) in three anatomical regions (the nasal cavity, nasopharynx and oropharynx) were compared and correlated. An independent sample t-test was used to assess the association between the 3D measurements of the upper airways and the otorhinolaryngological diagnosis of obstruction in the three anatomical regions. Inter- and intra-observer intraclass correlation coefficients were used to evaluate the reliability of the 3D measurements.

Results

The intra-class correlation coefficients ranged from 0.97 to 0.99. An association was found between turbinate hypertrophy and nasal cavity volume reduction (p < 0.05) and between adenoid hyperplasia and nasopharynx volume reduction (p < 0.001). No association was found between palatine tonsil hyperplasia and oropharynx volume reduction.

Conclusions

(1) The nasal cavity volume was reduced when hypertrophic turbinates were diagnosed; (2) the nasopharynx was reduced when adenoid hyperplasia was diagnosed; and (3) the oropharynx volume of mouth-breathing children with tonsil hyperplasia was similar to that of non-obstructed mouth-breathing children. The adoption of the actual anatomy of the various compartments of the upper airway is an improvement to the evaluation method.

Simulation of the upper airways in patients with obstructive sleep apnea and nasal obstruction: A novel finite element method

Objective

To evaluate the biomechanical properties of the soft palate and velopharynx in patients with obstructive sleep apnea (OSA) and nasal obstruction.

Study design

Prospective experimental study.

Materials and methods

Two finite element (FE) models of the soft palate were created in six patients undergoing nasal surgery, one homogeneous model based on CT images, and one layered model based on soft tissue composition. The influence of anatomy on displacement caused by a gravitational load and closing pressure were evaluated in both models. The strains in the transverse and longitudinal direction were obtained for each patient.

Results

The individual anatomy influences both its structural stiffness and its gravitational displacement. The soft palate width was the sole anatomical parameter correlated to the critical closing pressure, but the maximal displacement due to gravity may have a relationship to closing pressure of possibly an exponential order. The airway occlusion occurred mainly at the lateral attachments of the soft palate. The total transverse strain showed a strong correlation with maximal closing pressure. There was no relationship between the critical closing pressure and the preoperative AHI levels, or the change in AHI after surgery.

Conclusion

Hyperelastic FE models both in the homogeneous and layered model represent a novel method of evaluating soft tissue biomechanics of the upper airway. The obstruction occurs mainly at the level of the lateral attachments to the pharyngeal wall, and the width of the soft palate is an indicator of the degree of critical closing pressure. A less negative closing pressure corresponds to small total transverse strain. The effect of nasal surgery on OSA is most likely not explained by change in soft palate biomechanics.

Level of Evidence

NA.

Effect of Clark's twin-block appliance (CTB) and non-extraction fixed mechano-therapy on the pharyngeal dimensions of growing children

Introduction:

Narrow airway dimensions due to mandibular deficiency can predispose an individual to severe respiratory distress. Hence, treatment with mandibular advancement devices at an early age might help improving the pharyngeal passage and reduce the risk of respiratory difficulties. Therefore, the aim of the current study was to evaluate the mean changes in the pharyngeal dimensions of children with mandibular deficiency treated with Clark's twin-block appliance (CTB) followed by fixed orthodontic treatment.

Methods:

Orthodontic records of 42 children with mandibular deficiency were selected. Records comprised three lateral cephalograms taken at the start of CTB treatment, after CTB removal and at the end of fixed appliance treatment, and were compared with 32 controls from the Bolton-Brush study. Friedman test was used to compare pre-treatment, mid-treatment and post-treatment pharyngeal dimensions. Wilcoxon signed rank test was used to compare the airway between pre-treatment and post follow-up controls. Mann-Whitney U test was applied to compare the mean changes in pharyngeal dimensions between treatment group and controls from T₂ to T₀. Post-hoc Dunnet T3 test was used for multiple comparisons of treatment outcomes after CTB and fixed appliances, taking a p-value of ≤ 0.05 as statistically significant.

Results:

Superior pharyngeal space (p < 0.001) and upper airway thickness (p = 0.035) were significantly increased after CTB, and the change in superior pharyngeal space remained stable after fixed mechano-therapy.

Conclusion:

CTB can have a positive effect in improving pharyngeal space and the resultant increase in airway remains stable on an average of two and a half years.

Comparative Evaluation of the Pharyngeal Airway Space in Unilateral and Bilateral Cleft Lip and Palate Individuals with Noncleft Individuals: A Cone Beam Computed Tomography Study

Objective

To evaluate the pharyngeal airway space changes in complete unilateral cleft lip and palate (UCLP) and bilateral cleft lip and palate (BCLP) individuals, and compare with age and sex-matched noncleft (NC) control subjects.

Design

Retrospective study.

Setting

Cleft and Craniofacial Centre, KK Women's and Children's Hospital, Singapore.

Materials and Methods

Twenty UCLP (mean age: 13.4 ± 0.5 years), 18 BCLP (mean age: 13.5 ± 0.5 years) and 20 skeletal Class I subjects (mean age: 13.4 ± 0.6 years) were included in the study. Cone beam computed tomography scans were assessed for pharyngeal airway space (PAS) (oropharyngeal, nasopharyngeal, total airway space volume), and compared with PAS of age and sex-matched skeletal Class I NC individuals.

Results

Pharyngeal airway space showed statistically significant differences in the UCLP, BCLP, and NC control subjects. Oropharyngeal (9338 ± 1108 mm3, P < .05), nasopharyngeal (2911 ± 401 mm3, P < .05), and total airway space (12 250 ± 1185 mm3, P < .05) volumes of BCLP individuals showed significant reduction in comparison to UCLP and NC. There were no gender differences of PAS in any of the groups tested ( P > .05).

Conclusion

The pharyngeal airway space was significantly reduced in the BCLP group than were those in UCLP and control groups. This reduced PAS should be taken into account when planning treatment for these individuals.

Two-dimensional and volumetric airway changes after bimaxillary surgery for class III malocclusion

OBJECTIVES

Any change in maxilla and mandible position can alter the upper airway, and any decrease in the upper airway can cause sleep disorders. Thus, it is necessary to assess airway changes after repositioning of the maxilla and mandible during orthognathic surgery. The purpose of this study was to evaluate linear and volumetric changes in the upper airway after bimaxillary surgery to correct class III malocclusion via cone-beam computed tomography (CBCT) and to identify correlations between linear and volumetric changes.

MATERIALS AND METHODS

This was a prospective cohort study. CBCTs from 10 class III patients were evaluated before surgery and three months after. The Wilcoxon one-sample test was used to evaluate the differences in measurements before and after surgery. Spearman's rank correlation coefficient was used to test the correlation between linear and volumetric changes.

RESULTS

The results show that the nasopharyngeal space increased significantly, and that this increase correlated with degree of maxillary advancement. No significant changes were found in volumes before and after surgery. A correlation was found between linear and volumetric oropharyngeal changes.

CONCLUSION

Bimaxillary surgical correction of class III malocclusion did not cause statistically significant changes in the posterior airway space.

Three-dimensional analysis of craniofacial bones and soft tissues in obstructive sleep apnea using cone beam computed tomography

A total of 154 adult patients with sleep complaints underwent a polysomnography and a craniofacial cone beam computed tomography (CBCT). OSA was defined as an apnea and hypopnea index (AHI) or an oxygen desaturation index (ODI) ≥ 10. Soft tissues and craniofacial bones volumes were prospectively measured by CBCT and collected blindly from sleep polysomnography. Among the study patients, 127 (83%) suffered from OSA and 27 (17%) did not. OSA patients demonstrated a narrower maxillo-palatine core volume (11.7±3.2 vs 14.6±4.9cm³) even when adjusting for age, gender, height, neck circumference and body mass index. These upper airway measures provide a comprehensive analysis of bony structures and soft tissues, which can be involved in OSA.

Three-dimensional analyses of palatal morphology and its relation to upper airway area in obstructive sleep apnea

OBJECTIVE

To evaluate the relationship between palatal morphology and pharyngeal airway morphology in patients who have obstructive sleep apnea (OSA) and compare with a nonsnoring and nonapneic control group.

MATERIALS AND METHODS

Three-dimensional maxillary dental cast measurements from 25 OSA patients (6 women, 19 men) with a mean age of 41.5 (4.8) years, and 25 control group participants (14 women, 11 men) without any symptom of OSA with a mean age of 38.3 (3.7) were correlated with an analysis of pharyngeal area evaluated with lateral cephalograms. Intermolar and intercanine widths and palatal volumes were calculated on the dental casts, and the upper airway area measurements were performed on lateral cephalograms.

RESULTS

OSA patients had smaller oropharyngeal volume and upper airway when compared with controls (P < .001). Palatal area measurements were significantly smaller in OSA (P < .001). OSA patients had significantly narrower maxilla with smaller intermolar and intercanine widths (P < .001). A positive correlation was found between the palatal morphology and pharyngeal dimensions.

CONCLUSIONS

A significant correlation exists between palatal morphology and pharyngeal airway.

Are three-dimensional airway evaluations obtained through computed and cone-beam computed tomography scans predictable from lateral cephalograms? A systematic review of evidence

OBJECTIVE

To systematically review the literature correlating upper airway parameters between lateral cephalograms (LC) and cone-beam computed tomography (CBCT) or computed tomography (CT) scans to determine the utility of using LC to predict three-dimensional airway parameters.

MATERIALS AND METHODS

Both electronic and manual searches of the included studies were performed by two reviewers, and the quality of the studies that met selection criteria were assessed.

RESULTS

A total of 11 studies from the literature met the selection criteria. Assessed outcome variables showed correlation r < .7 between the LC and CT scans. The correlation between the LC and CBCT ranged from weak to strong with -.78 ≤ r and r ≤ .93 reported in the nasopharyngeal segment. In the oropharyngeal segment, a weak to strong correlation was reported with a range of -37 ≤ r and r ≤ .83 between the CBCT and LC. All associations in the hypopharyngeal segment showed a weak correlation. Four of studies were of weak quality, five were of moderate quality, and two were rated to be of strong quality.

CONCLUSION

No strong correlations were reported between the LC and CT scans. However, the LC-derived adenoid-nasopharyngeal ratio and the linear measurement (posterior nasal spine, PNS, to posterior pharyngeal wall) had a strong correlation with upright nasopharyngeal area and volume in the CBCTs. The area measurement in conventional LC can be also used as an initial screening tool to predict the upright three-dimensional oropharyngeal volumetric data. The variability of the hypopharyngeal segment cannot be predicted by LCs. However, more well-designed studies are needed to determine the clinical utility of using LC to predict airway size.

Changes in the oropharyngeal airway of Class II patients treated with the mandibular anterior repositioning appliance

OBJECTIVE

 To evaluate the effects of functional appliance treatment on the oropharyngeal airway volume, airway dimensions, and anteroposterior hyoid bone position of growing Class II patients.

MATERIALS AND METHODS

 Twenty Class II white patients (mean age, 11.7 ± 1.75 years) treated with the MARA followed by fixed appliances were matched to an untreated control sample by cervical vertebrae maturation stage at pretreatment (T1) and posttreatment (T2) time points. Cone beam computed tomography scans were taken at T1 and T2. Dolphin3D imaging software was used to determine oropharyngeal airway volume, dimensions, and anteroposterior hyoid bone position.

RESULTS

 Multivariate ANOVA was used to evaluate changes between T1 and T2. Oropharyngeal airway volume, airway dimensions, and A-P position of the hyoid bone increased significantly with functional appliance treatment. SNA and ANB decreased significantly in the experimental group (P ≤ .05). Changes in SNB and Sn-GoGn failed to reach statistical significance.

CONCLUSIONS

 Functional appliance therapy increases oropharyngeal airway volume, airway dimensions, and anteroposterior hyoid bone position in growing patients.

Importance of cephalographs in diagnosis of patients with sleep apnea

Introduction:

Obstructive sleep apnea (OSA) is considered to be a potentially life threatening disorder, which is characterized by repeated collapse of the upper airway during sleep with cessation of breathing. The cephalometric method despite being a static, two-dimensional evaluation of dynamic three-dimensional structures of the head and neck is useful in diagnosing patients with OSA, as they have shown that significant differences exist between asymptomatic controls and patients with OSA.

Aims and Objectives:

This study is designed to compare and validate the craniofacial morphology in patients with OSA using lateral cephalometry in both upright and supine position.

Materials and Methods:

Sixty subjects participated in the study of which 30 were patients with OSA diagnosed by questionnaire and 30 were healthy control group with age range of 25–45 years.

Results:

The study group demonstrated an increased ANB, mandibular plane angles (GoGn-SN), lower anterior facial height which are statistically significant with a significant P < 0.05. Significant decrease in posterior airway space, increased soft palate length, tongue length, and thickness suggesting reduced airway space in supine posture.

Conclusion:

Evaluation of craniofacial morphology in OSA patients using lateral cephalometry helps in recognizing the morphological changes induced by altered sleep pattern and for appropriate treatment planning.

Effect of body position on vocal tract acoustics: Acoustic pharyngometry and vowel formants

The anatomic basis and articulatory features of speech production are often studied with imaging studies that are typically acquired in the supine body position. It is important to determine if changes in body orientation to the gravitational field alter vocal tract dimensions and speech acoustics. The purpose of this study was to assess the effect of body position (upright versus supine) on (1) oral and pharyngeal measurements derived from acoustic pharyngometry and (2) acoustic measurements of fundamental frequency (F0) and the first four formant frequencies (F1-F4) for the quadrilateral point vowels. Data were obtained for 27 male and female participants, aged 17 to 35 yrs. Acoustic pharyngometry showed a statistically significant effect of body position on volumetric measurements, with smaller values in the supine than upright position, but no changes in length measurements. Acoustic analyses of vowels showed significantly larger values in the supine than upright position for the variables of F0, F3, and the Euclidean distance from the centroid to each corner vowel in the F1-F2-F3 space. Changes in body position affected measurements of vocal tract volume but not length. Body position also affected the aforementioned acoustic variables, but the main vowel formants were preserved.

Diagnosis and treatment for obstructive sleep apnea: Fundamental and clinical knowledge in obstructive sleep apnea

PURPOSE

This review article covers the diagnosis and treatment of obstructive sleep apnea (OSA) from a dental perspective. It addresses the issue of when and how to screen for and then, if indicated, refer the patient for a more comprehensive.

STUDY SELECTION

Our focus in this article was on identifying current unanswered questions that relevant to OSA problems that dental scientists have to pursue and on providing valuable information on that problems, consequently the previous studies which investigated or reviewed the diagnosis and treatment of OSA were included. In addition, we included studies on jaw movements during sleep and on the use of a lateral cephalometric film related to the diagnosis and treatment of OSA.

RESULTS

The role of portable sleep monitoring devices versus full laboratory polysomnography is discussed. This review also describes what is known about the efficacy of mandibular advancement devices and when and how they fit in to a treatment program for a patient with obstructive sleep apnea. Finally some basic research is presented on jaw movements during sleep and how a lateral cephalometric film can be used to assess the changes of the airway with body posture and head posture.

CONCLUSION

This article provides the valuable suggestions for the clinical questions in the diagnosis and treatment of OSA.

Evaluation of pharyngeal airway space changes after bimaxillary orthognathic surgery with a 3-dimensional simulation and modeling program

INTRODUCTION

The aims of this study were to use 3-dimensional simulation and modeling programs to evaluate the effects of bimaxillary orthognathic surgical correction of Class III malocclusions on pharyngeal airway space volume, and to compare them with the changes in obstructive sleep apnea measurements from polysomnography.

METHODS

Twenty-five male patients (mean age, 21.6 years) with mandibular prognathism were treated with bilateral sagittal split osteotomy and LeFort I advancement. Polysomnography and computed tomography were performed before surgery and 1.4 ± 0.2 years after surgery. All computed tomography data were transferred to a computer, and the pharyngeal airway space was segmented using SimPlant OMS (Materialise Medical, Leuven, Belgium) programs. The pretreatment and posttreatment pharyngeal airway space determinants in volumetric, linear distance, and cross-sectional measurements, and polysomnography changes were compared with the paired samples t test. Pearson correlation was used to analyze the association between the computed tomography and polysomnography measurements.

RESULTS

The results indicated that setback procedures produce anteroposterior narrowing of the pharyngeal airway space at the oropharyngeal and hypopharyngeal levels and the middle and inferior pharyngeal volumes (P <0.05). In contrast, advancement of the maxilla causes widening of the airway in the nasopharyngeal and retropalatal dimensions and increases the superior pharyngeal volume (P <0.05). Distinctively, bimaxillary orthognathic surgery induces significant increases in the total airway volume and the transverse dimensions of all airway areas (P <0.05). Significant correlations were found between the measurements on the computed tomography scans and crucial polysomnography parameters.

CONCLUSIONS

Bimaxillary orthognathic surgery for correction of Class III malocclusion caused an increase of the total airway volume and improvement of polysomnography parameters. A proposed treatment plan can be modified according to the risk of potential airway compromise or even to improve it with 3-dimensional imaging techniques and polysomnography.

A comprehensive assessment of genioglossus electromyographic activity in healthy adults

The genioglossus (GG) is an extrinsic muscle of the human tongue that plays a critical role in preserving airway patency. In the last quarter century, >50 studies have reported on respiratory-related GG electromyographic (EMG) activity in human subjects. Remarkably, of the studies performed, none have duplicated subject body position, electrode recording locations, and/or breathing task(s), making interpretation and integration of the results across studies extremely challenging. In addition, more recent research assessing lingual anatomy and muscle contractile properties has identified regional differences in muscle fiber type and myosin heavy chain expression, giving rise to the possibility that the anterior and posterior regions of the muscle fulfill distinct functions. Here, we assessed EMG activity in anterior and posterior regions of the GG, across upright and supine, in rest breathing and in volitionally modulated breathing tasks. We tested the hypotheses that GG EMG is greater in the posterior region and in supine, except when breathing is subject to volitional modulation. Our results show differences in the magnitude of EMG (%regional maximum) between anterior and posterior muscle regions (7.95 ± 0.57 vs. 11.10 ± 0.99, respectively; P < 0.001), and between upright and supine (8.63 ± 0.73 vs. 10.42 ± 0.90, respectively; P = 0.008). Although the nature of a task affects the magnitude of EMG (P < 0.001), the effect is similar for anterior and posterior muscle regions and across upright and supine (P > 0.2).

Detection of Obstructive sleep apnea in awake subjects by exploiting body posture effects on the speech signal

Obstructive sleep apnea (OSA) is a common sleep disorder. OSA is associated with several anatomical and functional abnormalities of the upper airway. It was shown that these abnormalities in the upper airway are also likely to be the reason for increased rate of apneic events in the supine position. Functional and structural changes in the vocal tract can affect the acoustic properties of speech. We hypothesize that acoustic properties of speech that are affected by body position may aid in distinguishing between OSA and non-OSA patients. We aimed to explore the possibility to differentiate OSA and non-OSA patients by analyzing the acoustic properties of their speech signal in upright sitting and supine positions. 35 awake patients were recorded while pronouncing sustained vowels in the upright sitting and supine positions. Using linear discriminant analysis (LDA) classifier, accuracy of 84.6%, sensitivity of 92.7%, and specificity of 80.0% were achieved. This study provides the proof of concept that it is possible to screen for OSA by analyzing and comparing speech properties acquired in upright sitting vs. supine positions. An acoustic-based screening system during wakefulness may address the growing needs for a reliable OSA screening tool; further studies are needed to support these findings.

Are temporomandibular disorders associated with habitual sleeping body posture or nasal septal deviation?

Numerous factors can be considered for the etiology of temporomandibular disorders (TMD). The aim of the present study was to investigate whether the presence of both nasal septal deviation (NSD) and habitual prone sleeping posture (HPSP) predisposes TMD. We evaluated 200 subjects in 4 groups. Group I (NSD-, HPSP-/control group), Group II (NSD+, HPSP-), Group III (NSD-, HPSP+), Group IV (NSD+, HPSP+). All patients were examined according to the research diagnostic criteria to determine the presence of TMD. Group IV had the highest value for TMD incidence (44 %). Thus, we found that the presence of both NSD and HPSP parameters increased TMD incidence in Group IV compared to the control group (p = 0.000). Additionally, Group IV showed significantly higher values than Group II (p = 0.012) and Group III (p = 0.039). For Group III (NSD-, HPSP+), TMD was determined higher compared to the control group (p = 0.009). A statistically higher value of presence of TMD was determined in Group II (NSD+, HPSP-) than control group (p = 0.029). The incidence of TMD was significantly higher in women than men (p = 0.020). We concluded that one having an unilateral obstructive nasal septal deviation in addition to a habit of sleeping in prone position must be alert for potential TMD.

Three-dimensional upper-airway assessment in patients with bronchial asthma

OBJECTIVE

To assess the upper airway (UAW) total volume (TV), the nasopharyngeal narrowest area (NNA), and the oropharyngeal narrowest area (ONA) in patients with bronchial asthma.

MATERIALS AND METHODS

The sample consisted of 52 patients divided into two groups: the control group (n  =  26; mean age  =  14.85 years), which consisted of patients not suffering from bronchial asthma; and the asthmatic group (n  =  26; mean age  =  16.65 years), which consisted of patients with bronchial asthma. To assess UAW-related variables (TV, NNA, and ONA), cone-beam computed tomography scans of the patients were evaluated by means of the Dolphin Imaging software 11.5. All measurements were repeated after 30 days, and the results were submitted to reliability tests by means of the intraclass correlation coefficient and the Bland-Altman agreement test. The values obtained for TV, NNA, and ONA for each group were compared by using Student's t-test for independent samples (5% level of significance).

RESULTS

The results showed that the groups were matched concerning gender, cephalometric characteristics, and type of malocclusion. The asthmatic group had significantly lower TV (P  =  .01) and ONA (P  =  .007) than the control group. However, no significant difference was observed for NNA between the groups (P  =  .54).

CONCLUSIONS

Bronchial asthma may be a determining factor for the reduction of UAW dimensions, as patients with asthma showed significant reductions in TV and ONA dimensions.

The relationship between upper airways and craniofacial morphology studied in 3D. A CBCT study

OBJECTIVES

To assess whether morphology and dimension of the upper airway differ between patients characterized by various craniofacial morphology.

SETTING AND SAMPLE POPULATION

Ninety young adult patients from the Postgraduate Clinic, Section of Orthodontics, Department of Dentistry, Health, Aarhus University, Denmark, with no obvious signs of respiratory diseases and no previous adeno-tonsillectomy procedures. Thirty patients were characterized as Class I (-0.5 < ANB < 4.5), 30 as Class II (ANB > 4.5), and 30 as Class III (ANB < -0.5).

MATERIAL AND METHODS

Cone-beam computed tomography (CBCT) scans obtained in a supine position for all patients. Cephalometric landmarks were identified in 3D. Sagittal and transversal dimensions, cross sections, and partial and total volumes of the upper airway were correlated with the cephalometric measurements in all three planes of space. The cross-sectional minimal area of the upper airway was assessed as well.

RESULTS

No statistical significant relationships between dimension and morphology of upper airways and skeletal malocclusion were found.

CONCLUSION

Differences in craniofacial morphology as identified by the sagittal jaw relationship were not correlated with variation in upper airway volumes. A clinical significant relation was detected between minimal area and total upper airway volume.

Videofluoroscopic investigation of body position on articulatory positioning

PURPOSE

To quantitatively examine the effects of body position on the positioning of the epiglottis, tongue, and velum at rest and during speech.

METHOD

Videofluoroscopic data were obtained from 12 healthy adults in the supine and upright positions at rest and during speech while the participants produced 12 VCV sequences. The effects of body position, target sounds, and adjacent sounds on structural positioning and vowel formant structure were investigated.

RESULTS

Velar retropositioning in the supine position was the most consistent pattern observed at rest. During speech, all structures, with varying degrees of adjustment, appeared to work against the gravitational pull, resulting in no significant narrowing in the oro- and nasopharyngeal regions while in the supine position. Minimal differences in the formant data between the body positions were also observed. Overall, structural positioning was significantly dependent on the target and adjacent sounds regardless of body position.

CONCLUSIONS

The present study demonstrated that structural positioning in response to gravity varied across individuals based on the type of activities being performed. With varying degrees of positional adjustment across different structures, fairly consistent articulatory positioning in the anterior-posterior dimension was maintained in different body positions during speech.

Three-dimensional evaluation of the pharyngeal airway volumes in patients affected by unilateral cleft lip and palate

INTRODUCTION

Patients affected by cleft lip and palate often have complaints of snoring and respiratory difficulties during sleep. The purposes of this study were to evaluate nasopharyngeal, oropharyngeal, and total airway volumes of patients affected by unilateral cleft lip and palate and to compare them with a well-matched control group without unilateral cleft lip and palate using cone-beam computed tomography.

METHODS

The study sample consisted of 60 patients (26 girls, 34 boys) divided into 2 groups: unilateral cleft lip and palate (20 boys, 10 girls; 8 right sided, 22 left sided; mean age, 14.6 ± 3.2 years) and no cleft (control group; 14 boys, 16 girls; mean age, 14.8 ± 2.8 years). Nasopharyngeal, oropharyngeal, and total airway volumes of the subjects in both groups were calculated 3 dimensionally with cone-beam computed tomography. Group differences in relation to cleft side, sex, and cleft presence were statistically tested at P <0.05.

RESULTS

Patients affected by unilateral cleft lip and palate had similar airway volumes regardless of the side of the cleft. In addition, no statistically significant differences were found between the sexes in the 2 groups. Patients affected by unilateral cleft lip and palate had smaller nasopharyngeal, oropharyngeal, and total airway volumes when compared with the control group. The difference for oropharyngeal airway volume (-4036.7 mm(3)) was statistically significant (P <0.05), whereas nasopharyngeal volume (-21.6 mm(3)) and total airway volume (-4057.3 mm(3)) differences were not significant (P >0.05).

CONCLUSIONS

Patients affected by unilateral cleft lip and palate had decreased volumes of oropharyngeal (P <0.05) and total (P >0.05) airways compared with the well-matched control group without unilateral cleft lip and palate.