Comparative analysis of upper airway volume with lateral cephalograms and cone-beam computed tomography

Correlation analysis of airway-facial phenotype in Crouzon syndrome by geometric morphometrics: A promising method for non-radiation airway evaluation

AIM

This study aimed to verify the correlation of the airway-facial phenotype and visualize the morphological variation in Crouzon syndrome patients. Additionally, to develop a non-radiation methodology for airway assessments.

METHOD

In this study, 22 patients diagnosed with Crouzon syndrome (Age: 7.80 ± 5.63 years; Gender distribution: 11 females and 11 males) were analysed. The soft tissue surface and airway were three-dimensionally reconstructed, and the entire facial phenotype was topologized and converted into spatial coordinates. Geometric morphometrics was employed to verify the correlation and visualize dynamic phenotypic variation associated with airway volume. A total of 276 linear variables were automatically derived from 24 anatomical landmarks, and principal component analysis (PCA) identified the 20 most significant parameters for airway evaluation. Correlation analyses between parameters and airway volume were performed. Then, patients were classified into three groups based on airway volume, and the differences among the groups were compared for evaluating the differentiating effectiveness of parameters.

RESULTS

The facial phenotype was strongly correlated with the airway (coefficient: 0.758). Morphological variation was characterized by (i) mandibular protrusion and anticlockwise rotation; (ii) midface retrusion; (iii) supraorbital frontward and (iv) lengthening of the facial height. All the anthropometric parameters were strongly associated with the airway, and the differences among the groups were statistically significant.

CONCLUSION

This study confirmed the strong correlation between facial phenotype and airway parameters in Crouzon syndrome patients. Despite the development of the airway, pathological midface retrusion was still aggravated, suggesting that surgical intervention was inevitable. Three-dimensional facial anthropometry has potential as a non-radiation examination for airway evaluation.

Effects of adenoid hypertrophy on nasopharyngeal airway ventilation: A computational fluid dynamics study

OBJECTIVES

Adenoid hypertrophy causes impaired nasopharyngeal airways (NA) ventilation. However, it is difficult to evaluate the ventilatory conditions of NA. Therefore, this study aimed to analyze the nasopharyngeal airway resistance (NARES) based on computational fluid dynamics simulations and the nasopharyngeal airway depth (NAD) and adenoid hypertrophy grade measured on cephalometric cone-beam computed tomography images and determine the relationship between NAD and grade and NARES to ultimately assess using cephalometric measurements whether NA has airway obstruction defects.

METHODS

Cephalogram images were generated from cone-beam computed tomography data of 102 children (41 boys; mean age: 9.14 ± 1.43 years) who received orthodontic examinations at an orthodontic clinic from September 2012 to March 2023, and NAD and adenoid grade and NARES values were measured based on computational fluid dynamics analyses using a 3D NA model. Nonlinear regression analyses were used to evaluate the relationship between NARES and NAD and correlation coefficients to evaluate the relationship between grade and NARES.

RESULTS

NARES was inversely proportional to the cube of NAD (R2 = 0.786, P < 0.001), indicating a significant relationship between these variables. The resistance NARES increased substantially when the distance NAD was less than 5 mm. However, adenoid Grade 4 (75 % hypertrophy) was widely distributed.

CONCLUSIONS

These study findings demonstrate that the ventilatory conditions of NA can be determined based on a simple evaluation of cephalogram images. An NAD of less than 5 mm on cephalometric images results in NA obstruction with substantially increased airflow resistance.

Comparison of PAS and adenoids in patients with and without maxillary micrognathia before orthodontic treatment

OBJECTIVE

Craniofacial anomalies are widely discussed as predisposing factors of breathing disorders. Since many more cofactors exist, this study investigated the association between maxillary micrognathia and morphological changes of posterior airway space and adenoids in these patients.

MATERIAL AND METHODS

Cephalometric radiographs of n = 73 patients were used for data acquisition. The patients were divided into two groups according to certain skeletal characteristics: maxillary micrognathia (n = 34, 16 female, 18 male; mean age 10.55 ± 3.03 years; defined by a SNA angle < 79°) and maxillary eugnathia (n = 39, 19 female, 20 male; mean age 10.93 ± 3.26 years; defined by a SNA angle > 79°). The evaluation included established procedures for measurements of the maxilla, posterior airway space and adenoids. Statistics included Kolmogorov-Smirnov-, T- and Mann-Whitney-U-Tests for the radiographs. The level of significance was set at p < 0.05.

RESULTS

The cephalometric analysis showed differences in the superior posterior face height and the depth of the posterior airway space at palatal level among the two groups. The depth of the posterior airway space at mandibular level was the same for both groups, just as the size of the area taken by adenoids in the nasopharynx.

CONCLUSIONS

Skeletal anomalies affect the dimension of the posterior airway space. There were differences among the subjects with maxillary micrognathia and these with a normal maxilla. However, the maxilla was only assessed in the sagittal direction, not in the transverse. This study showed that the morphology of the maxilla relates to the posterior airway space whereas the adenoids seem not to be affected.

CLINICAL RELEVANCE

Maxillary micrognathia is significantly associated with a smaller depth of the posterior airway space at the palatal level compared to patients with maxillary eugnathia.

Assessment of upper airway changes after interpositional arthroplasty: a cephalometric analysis

This prospective cohort study examined the changes in airway area and soft tissue parameters following interpositional arthroplasty for temporomandibular joint (TMJ) ankylosis. Ten patients with TMJ ankylosis underwent surgery, and preoperative and postoperative skeletal and soft tissue measurements were obtained. A significant rise in soft tissue parameters was observed following surgery, although only minor changes in skeletal parameters were seen. The nasoropharyngeal area, oral area, soft palate area, and tongue area were examined. After the surgery, increases in values were observed in the nasoropharyngeal area (from 3482.4 mm2 to 3618.7 mm2), the oral area (from 2731.8 mm2 to 2840.8 mm2), the soft palate area (from 204.9 mm2 to 217.3 mm2), and the tongue area (from 2577.5 mm2 to 2600.8 mm2). These findings suggest that interpositional arthroplasty can improve airway area and soft tissue dimensions, affecting the stomatognathic system's aesthetic and functional aspects. Further research is needed to validate these results and assess long-term stability.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Exploring the Intricate Links between Adenotonsillar Hypertrophy, Mouth Breathing, and Craniofacial Development in Children with Sleep-Disordered Breathing: Unraveling the Vicious Cycle

Adenotonsillar hypertrophy has been well-acknowledged as the primary instigator of sleep-disordered breathing in the pediatric population. This condition spans a spectrum, from typical age-related growth that the immune system influences to persistent pathological hypertrophy. Reduction in air spaces, metabolic changes, neurobehavioral alterations, and chronic inflammation characterizes the latter form. As the go-to treatment, adenotonsillectomy has proven effective. However, it is not a guarantee for all patients, leaving us without reliable predictors of treatment success. Evidence suggests a connection between adenotonsillar hypertrophy and specific oral breathing patterns resulting from craniofacial development. This finding implies an intricate interdependence between the two, hinting at a self-sustaining vicious cycle that persists without proper intervention. The theories regarding the relationship between craniofacial conformation and sleep-disordered breathing have given rise to intriguing perspectives. In particular, the "gracilization theory" and the "gravitational hypothesis" have provided fascinating insights into the complex interaction between craniofacial conformation and SDB. Further investigation is crucial to unraveling the underlying pathophysiological mechanisms behind this relationship. It is also vital to explore the risk factors linked to adenotonsillectomy failure, study the long-term effects of adenotonsillar hypertrophy on craniofacial growth, and devise innovative diagnostic techniques to detect upper airway compromise early. Moreover, to assess their efficacy, we must delve into novel therapeutic approaches for cases that do not respond to traditional treatment, including positional therapy and orofacial myofunctional therapy. Though complex and unpredictable, these challenges promise to enhance our understanding and treatment of adenotonsillar hypertrophy and its related complications in children. By taking on this task, we can pave the way for more effective and targeted interventions, ultimately improving affected individuals' well-being and quality of life.

Effect of different degrees of adenoid hypertrophy on pediatric upper airway aerodynamics: a computational fluid dynamics study

To improve the diagnostic accuracy of adenoid hypertrophy (AH) in children and prevent further complications in time, it is important to study and quantify the effects of different degrees of AH on pediatric upper airway (UA) aerodynamics. In this study, based on computed tomography (CT) scans of a child with AH, UA models with different degrees of obstruction (adenoidal-nasopharyngeal (AN) ratio of 0.9, 0.8, 0.7, and 0.6) and no obstruction (AN ratio of 0.5) were constructed through virtual surgery to quantitatively analyze the aerodynamic characteristics of UA with different degrees of obstruction in terms of the peak velocity, pressure drop (△P), and maximum wall shear stress (WSS). We found that two obvious whirlpools are formed in the anterior upper part of the pediatric nasal cavity and in the oropharynx, which is caused by the sudden increase in the nasal cross-section area, resulting in local flow separation and counterflow. In addition, when the AN ratio was ≥ 0.7, the airflow velocity peaked at the protruding area in the nasopharynx, with an increase 1.1-2.7 times greater than that in the nasal valve area; the △P in the nasopharynx was significantly increased, with an increase 1.1-6.8 times greater than that in the nasal cavity; and the maximum WSS of the posterior wall of the nasopharynx was 1.1-4.4 times larger than that of the nasal cavity. The results showed that the size of the adenoid plays an important role in the patency of the pediatric UA.

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.

Evaluation of computational fluid dynamics models for predicting pediatric upper airway airflow characteristics

Computational fluid dynamics (CFD) has the potential for use as a clinical tool to predict the aerodynamics and respiratory function in the upper airway (UA) of children; however, careful selection of validated computational models is necessary. This study constructed a 3D model of the pediatric UA based on cone beam computed tomography (CBCT) imaging. The pediatric UA was 3D printed for pressure and velocity experiments, which were used as reference standards to validate the CFD simulation models. Static wall pressure and velocity distribution inside of the UA under inhale airflow rates from 0 to 266.67 mL/s were studied by CFD simulations based on the large eddy simulation (LES) model and four Reynolds-averaged Navier-Stokes (RANS) models. Our results showed that the LES performed best for pressure prediction; however, it was much more time-consuming than the four RANS models. Among the RANS models, the Low Reynolds number (LRN) SST k-ω model had the best overall performance at a series of airflow rates. Central flow velocity determined by particle image velocimetry was 3.617 m/s, while velocities predicted by the LES, LRN SST k-ω, and k-ω models were 3.681, 3.532, and 3.439 m/s, respectively. All models predicted jet flow in the oropharynx. These results suggest that the above CFD models have acceptable accuracy for predicting pediatric UA aerodynamics and that the LRN SST k-ω model has the most potential for clinical application in pediatric respiratory studies.

Analysis of Risk Factors for Otitis Media with Effusion in Children with Adenoid Hypertrophy

Objective

This study aimed to explore whether children with AH have a higher obesity prevalence and analyze the risk factors for otitis media with effusion(OME) in AH children.

Methods

AH patients aged 3-12 years old that were hospitalized in our hospital for adenoidectomy from June 2020 to September 2022 were included in this study. Height and weight were measured to calculate the body mass index, weight for height and weight z-score to evaluate the development of AH children. Propensity score matching was applied to minimize patient selection bias and adjust for confounding factors to analyze the risk factors for OME in children with AH.

Results

A total of 887 children with AH were enrolled in this study. The prevalence of overweight or obesity was higher in children with AH than the control group. The size of adenoids is significantly different between AH children with and without OME. For children aged over 5, there are significantly higher counts of white blood cells, neutrophils, and monocytes in the AH children with OME than those without OME. More individuals represent to be atopic in children with OME than those without OME.

Conclusion

The obstruction of the Eustachian tube is the most important factor of OME in AH children. It seems that there is no apparent correlation between OME and atopic conditions in AH children. In addition to surgical resection of adenoids, active control of infection and inflammation are also important to prevent OME for AH children aged over 5.

Validation and comparison of volume measurements using 1 multidetector computed tomography and 5 cone-beam computed tomography protocols: An in vitro study

Purpose

The purpose of this study was to compare volume measurements obtained using 2 image software packages on Digital Imaging and Communications in Medicine (DICOM) images acquired from 1 multidetector computed tomography and 5 cone-beam computed tomography devices, using different protocols for physical volume measurements.

Materials and Methods

Four pieces of bovine leg were prepared. Marrow was removed from 3 pieces, leaving cortical bone exposed. The resulting space of 1 piece was filled with water, another was filled with propylene glycol, and the third was left unfilled. The marrow in the fourth sample was left fully intact. Volume measurements were obtained after importing DICOM images into the Dolphin Imaging 11.95 and ITK-SNAP software programs. Data were analyzed using 3-way analysis of variance with a generalized linear model to determine the effects of voxel size, software, and content on percentage mean volume differences between tomographic protocols. A significance level of 0.05 was used.

Results

The intraclass correlation coefficients for intraobserver and interobserver reliability were, respectively, 0.915 and 0.764 for the Dolphin software and 0.894 and 0.766 for the ITK-SNAP software. Three sources of statistically significant variation were identified: the interaction between software and content (P=0.001), the main effect of content (P=0.014), and the main effect of software (P=0.001). Voxel size was not associated with statistically significant differences in volume measurements.

Conclusion

Both content and software influenced the accuracy of volume measurements, especially when the content had gray values similar to those of the adjacent tissues.

Influences of Airway Obstruction Caused by Adenoid Hypertrophy on Growth and Development of Craniomaxillofacial Structure and Respiratory Function in Children

Adenoid hypertrophy (AH) is a common disease in otorhinolaryngology. Children with chronic snoring and hypoxia are susceptible to long-term nasal obstruction, while long-term open-mouth breathing may cause craniofacial bone development disorders and dull facial expressions, the so-called adenoid face. The purpose of this work is to analyze the influence of AH-induced airway obstruction (AO) on the growth and development of craniomaxillofacial structure and respiratory function (RF) in children. The clinical data of 56 AH children (observation group) and 42 healthy children with physical examination (control group) who visited the Hebei Eye Hospital during the same period were retrospectively analyzed. All children received acoustic rhinometry and X-ray cephalometric measurements. The upper airway structure, sleep disorder score, and A/N value of nasopharyngeal lateral X-ray images were compared between cases and controls. For AH children, sleep tests were also performed to assess their RF. X-ray cephalometric measurements of facial morphology showed obvious vertical growth, mandibular retrognathia, and enlarged mandibular angle in AH children. AH mainly affects the size of the nasopharyngeal and oropharyngeal airway. AH children presented with higher nasal airway resistance (5.11 ± 1.95 cmH₂O/L min) and lower nasopharyngeal volume (NPV) (16.86 ± 3.93 cm³) than controls. Of the AH children, 45 had abnormal RF, including 4 with obstructive sleep apnea syndrome. The A/N value of nasopharyngeal lateral X-ray images was significantly higher in AH children than in controls. Besides, worse sleep quality was found in AH children. The above differences were all of statistical significance. The above indicates that AH can affect the size of the nasopharyngeal and oropharyngeal airway, change children's respiratory mode and RF, increase nasal resistance, and decrease NPV, resulting in upper respiratory tract stenosis, as well as craniomaxillofacial and oral malformations, which affects children's normal growth and development.

Adenoidal-Nasopharyngeal Ratio in Healthy Adults on Cone Beam Computed Tomography

OBJECTIVE

This study aimed to quantify the adenoidal-nasopharyngeal ratio (ANR) in a cohort of healthy adults on cone beam computed tomography (CT) using the Fujioka method, which is a reproducible measure of adenoid size and nasopharyngeal patency.

METHODS

Electronic health records and maxillofacial cone beam CT in 202 consecutive patients aged 16 years and older were retrospectively reviewed. Patients with a history of adenoidectomy, sinonasal disease, lymphoproliferative disorders, and cleft palate were excluded from the study. The midsagittal reconstructed cone beam CT image was used to determine the ANR. Statistical analysis was conducted using 1-way analysis of variance.

RESULTS

Of the 202 subjects, 131 were female and 71 were male. The mean ± SD subject age was 45.43 ± 20.79 years (range, 16-91 years). The mean ± SD ANR in all subjects was 0.22 ± 0.13 (range, 0.03-0.75) and in each decade of adult life was as follows: younger than 21 years, 0.39 ± 0.12; 21 to 30 years, 0.29 ± 0.11; 31 to 40 years, 0.21 ± 0.09; 41 to 50 years, 0.20 ± 0.07; 51 to 60 years, 0.16 ± 0.10; 61 to 70 years, 0.13 ± 0.05; 71 to 80 years, 0.12 ± 0.05; 81 to 90 years, 0.11 ± 0.04; and 91 years or older, 0.10 ± 0. The differences in mean ANR among the age subgroups were statistically significant (P < 0.001).

CONCLUSIONS

The mean ANR gradually decreased from 0.39 in the second decade of life to 0.16 in the sixth decade of life and plateaued at approximately 0.10 thereafter.

Relationship between craniofacial and dental arch morphology with pharyngeal airway space in adolescents

PURPOSE

The aim of the study was to investigate a possible relationship between pharyngeal airway space, craniofacial variables, and dental arch form in adolescents grouped by sex.

METHODS

This cross-sectional study included 108 adolescents aged between 12 and 17 years. Lateral cephalometric radiographs were used to analyze sagittal craniofacial variables and the pharyngeal airway space. For evaluation of the dental arch form, we used plaster models. Statistical analysis included Student's t‑test and Pearson's correlation coefficient (r).

RESULTS

Maxillary length was directly proportional to upper nasopharyngeal airway dimensions in males (r = 0.312, p = 0.021) and females (r = 0.310, p = 0.022). In the female group, upper oropharyngeal measurements showed an inverse correlation with a labial inclination of the upper incisors (r = -0.415, p = 0.001), protrusion of the upper incisors (r = -0.364, p = 0.006), and soft palate thickness (r = -0.27, p = 0.043). In the male group, upper nasopharynx measurements showed an inverse correlation with soft palate thickness (r = -0.277, p = 0.042). The upper arch form appeared to be related to oropharyngeal measurements in females, while the lower arch form was related to oropharyngeal dimensions in males.

CONCLUSION

The findings suggest that there are sex-dependent correlations of the nasopharyngeal and oropharyngeal airway space with the sagittal craniofacial morphology and the transversal dental arch form.

Assessment of pharyngeal airway in Korean adolescents according to skeletal pattern, sex, and cervical vertebral maturation: A cross-sectional CBCT study

Objective

To investigate airway volumes using cone-beam computed tomography (CBCT) by skeletal patterns, sex, and cervical vertebral maturation (CVM) stages in Korean adolescents.

Methods

The sample consisted of pretreatment CBCT and cephalograms of 95 adolescents (aged 12–19) obtained out of 1,611 patients examined for orthodontic treatment from 2018 to 2020 in Kyungpook National University Dental Hospital. The samples were classified into two sex groups; three skeletal pattern groups, four chronological age groups and four CVM stages. Nasopharyngeal volumes (NPV), oropharyngeal volumes (OPV), total pharyngeal airway volume (TAV) and minimum cross-sectional area (MCA) measurements were taken from the CBCT. Multiple linear regression analyses to find out which one of the independent variables are good predictors for airway variables. Significant factors were analyzed by two-way multivariate analysis of variance (MANOVA) then multiple comparisons were analyzed using a t-test, and Fisher least significant difference.

Results

Age, sex, CVM, and Sella-Nasion-B point have significant influence on airway variable. Males and females showed similar patterns of change in chronological age groups 1–3; however, males had larger NPV, OPV, and MCA at CVM in group 4. According to CVM stages, males had larger OPV, TAV, and MCA at CVM stage 6 (p-value 0.019, 0.021, 0.015, respectively) and no sex differences at CVM stages 3, 4, and 5.

Conclusions

Skeletal patterns have an effect on airway volume. Sex differences were found in CVM 6.

A Cone Beam CT Study of Upper Airway Morphology in Perimenopausal and Postmenopausal Women

Purpose

Menopause is accompanied by a decline in estrogen and progesterone. Several studies have demonstrated that upper airway patency decreases in women after menopause, while morphology changes are still a lack of evidence. This study aimed to explore upper airway morphology changes in perimenopausal and postmenopausal women.

Methods

This retrospective cross-sectional study included 367 consecutive Chinese female patients over 25 years old who had routinely taken large-field cone beam computed tomography in the imaging library of Peking University School and Hospital of Stomatology from October 2016 to September 2020. A total of 283 males were screened as sex controls according to the same age group. Upper airway morphology, hyoid position and facial pattern were measured. The association between perimenopausal and postmenopausal years and upper airway morphology in both sexes was analyzed.

Results

Perimenopausal women (aged 45-54 years) showed a significant decrease in the volume (3172.91mm³, 95% CI = 653.86-5691.96) and minimum cross-sectional area (37.08 mm², 95% CI = 5.36-68.80), and a significant increase in the length (-1.96mm, 95% CI = -3.62 to -0.29) of upper airway compared to adjacent reproductive years (aged 35-44), while this difference was neither seen in other adjacent two reproductive age groups of females nor in the same age groups of males. In postmenopausal women (55 years and older), hyoid position was significantly lower (-2.74mm, 95% CI = -4.42 to -1.07) than either age group, while no similar changes were seen in men.

Conclusion

Women had smaller airway volume, reduced upper airway cross-sectional area and longer airway length in perimenopausal years, and a significantly lower hyoid position in postmenopausal years. These changes may be related to menopause itself and independent of the changes associated with aging.

Aerodynamic characteristics in upper airways among orthodontic patients and its association with adenoid nasopharyngeal ratios in lateral cephalograms

BACKGROUND

Adenoid hypertrophy among orthodontic patients may be detected in lateral cephalograms. The study investigates the aerodynamic characteristics within the upper airway (UA) by means of computational fluid dynamics (CFD) simulation. Furthermore, airflow features are compared between subgroups according to the adenoidal nasopharyngeal (AN) ratios.

METHODS

This retrospective study included thirty-five patients aged 9-15 years having both lateral cephalogram and cone beam computed tomography (CBCT) imaging that covered the UA region. The cases were divided into two subgroups according to the AN ratios measured on the lateral cephalograms: Group 1 with an AN ratio < 0.6 and Group 2 with an AN ratio ≥ 0.6. Based on the CBCT images, segmented UA models were created and the aerodynamic characteristics at inspiration and expiration were simulated by the CFD method for the two groups. The studied aerodynamic parameters were pressure drop (ΔP), maximum midsagittal velocity (V_ms), maximum wall shear stress (P_ws), and minimum wall static pressure (P_w).

RESULTS

The maximum V_ms exhibits nearly 30% increases in Group 2 at both inspiration (p = 0.013) and expiration (p = 0.045) compared to Group 1. For the other aerodynamic parameters such as ΔP, the maximum P_ws, and minimum P_w, no significant difference is found between the two groups.

CONCLUSIONS

The maximum V_ms seems to be the most sensitive aerodynamic parameter for the groups of cases. An AN ratio of more than 0.6 measured on a lateral cephalogram may associate with a noticeably increased maximum V_ms, which could assist clinicians in estimating the airflow features in the UA.

Automated Adenoid Hypertrophy Assessment with Lateral Cephalometry in Children Based on Artificial Intelligence

Adenoid hypertrophy may lead to pediatric obstructive sleep apnea and mouth breathing. The routine screening of adenoid hypertrophy in dental practice is helpful for preventing relevant craniofacial and systemic consequences. The purpose of this study was to develop an automated assessment tool for adenoid hypertrophy based on artificial intelligence. A clinical dataset containing 581 lateral cephalograms was used to train the convolutional neural network (CNN). According to Fujioka's method for adenoid hypertrophy assessment, the regions of interest were defined with four keypoint landmarks. The adenoid ratio based on the four landmarks was used for adenoid hypertrophy assessment. Another dataset consisting of 160 patients' lateral cephalograms were used for evaluating the performance of the network. Diagnostic performance was evaluated with statistical analysis. The developed system exhibited high sensitivity (0.906, 95% confidence interval [CI]: 0.750-0.980), specificity (0.938, 95% CI: 0.881-0.973) and accuracy (0.919, 95% CI: 0.877-0.961) for adenoid hypertrophy assessment. The area under the receiver operating characteristic curve was 0.987 (95% CI: 0.974-1.000). These results indicated the proposed assessment system is able to assess AH accurately. The CNN-incorporated system showed high accuracy and stability in the detection of adenoid hypertrophy from children' lateral cephalograms, implying the feasibility of automated adenoid hypertrophy screening utilizing a deep neural network model.

Analysis of Airway and Midface in Crouzon Syndromes

BACKGROUND

Crouzon syndrome is associated with severe respiratory impairment of the upper airway due in part to midfacial dysmorphology. We calculated the distinctive nasal diameter and pharyngeal airway volume in patients with Crouzon syndrome and compared them with age-matched control subjects.

METHODS

Children with computed tomography scans in the absence of surgical intervention were included. Computed tomography scans were digitized and manipulated using Surgicase CMF (Materialise). Craniometric data relating to the midface and airway were collected. For all linear measurements, mean percent increases or decreases were calculated relative to the size of control subjects, and volumetric assessment of the airway was tabulated. Statistical analysis was performed using t test.

RESULTS

Twenty-six computed tomography scans were included (control n = 17, Crouzon n = 9). All children were in early mixed dentition. Pharyngeal airway volume was decreased in patients with Crouzon syndrome relative to control subjects by 46% (P = 0.003). The distance from the posterior tongue to the posterior pharyngeal wall decreased 31% when comparing the Crouzon group versus the control (P = 0.04).

CONCLUSIONS

Three-dimensional analysis revealed notably decreased pharyngeal and nasal airway volumes in patients with Crouzon syndrome, but nasal bone tissue and soft tissue measurements showed very little change between patients and control subjects.

Upper airways evaluation in young adults with an anterior open bite: A CBCT retrospective controlled and cross-sectional study

OBJECTIVE

To compare the dimensions of the upper airway in young adults with anterior open bite versus matched individuals with an adequate overbite (control group) using different measurement approaches (linear, area, and volume measures).

MATERIALS AND METHODS

The sample included 137 cone-beam computed tomographies (CBCTs) of young adults (74 men and 63 women) divided into two groups: 47 CBCTs of individuals (mean age 27.89) with open bite (overbite depth indicator (ODI) 56.84°±9.48° and Frankfort mandibular plane angle (FMA) 31.21°±6.44°) and 90 CBCTs of individuals (mean age 26.87) without an open bite (ODI 62.24°±9.47°, FMA 26.79°±5.81°). Two trained and calibrated orthodontists made all linear, area, and volume measurements on the CBCT records of the upper airways using Planmeca Romexis software. The Mann-Whitney U-test, chi-squared test, and multiple linear regression were applied. Significance was set at P<0.05.

RESULTS

There were no differences in linear or volume measurements between groups, but there was a greater area in the open bite group (greater mean difference between groups 928.3 mm²) than the control group. No variable influenced nasopharyngeal airway volume, but ANB angle affected oropharyngeal airway volume (β=-623.87) and total airway volume (β=-651.48).

CONCLUSIONS

Orthodontists should be aware that the airways diagnosis can vary depending on the measurement approach used, the volumetric method being the gold standard. The pharyngeal airway volume was similar in individuals with vs. without an open bite and is mainly influenced by ANB angle in both groups.

Cephalometric analysis of the pharyngeal airway space after maxillary advancement surgery

This study evaluated the effect of maxillary advancement surgery on the size of the pharyngeal airway space (PAS). Lateral cephalometric radiographs were collected for 90 patients (29 men and 61 women; average age, 27.2 ± 8.1 years) before (T1) and 1 year after (T2) maxillary advancement surgery. Horizontal and vertical changes in the maxilla and PAS were measured and classified by distance. The maxilla was advanced horizontally by 2.9 ± 1.7 mm and vertically by 2.7 ± 1.4 mm. Upward maxillary movement of ≥4 mm significantly increased PAS (mean change in PAS, 2.6 mm), and upward maxillary movement significantly decreased the posterior nasal spine to the P-point. Only patients with vertical advancement ≥4 mm and horizontal advancement of 3 mm had significant increases in all three PAS parameters. Although forward maxillary movement is believed to have a large effect on PAS, it is suggest that upward vertical movement is more effective for improving PAS. Both the extent and direction of maxillar movement should be considered. Future studies should use cone-beam computed tomography to evaluate the effect of axial direction and differences in PAS.

Adenoidal Disease and Chronic Rhinosinusitis in Children-Is there a Link?

Adenoid hypertrophy (AH) is an extremely common condition in the pediatric and adolescent populations that can lead to various medical conditions, including acute rhinosusitis, with a percentage of these progressing to chronic rhinosinusitis (CRS). The relationship between AH and pediatric CRS has been extensively studied over the past few years and clinical consensus on the treatment has now been reached, allowing this treatment to become the preferred clinical practice. The purpose of this study is to review existing literature and data on the relationship between AH and CRS and the options for treatment. A systematic literature review was performed using a search line for "(Adenoiditis or Adenoid Hypertrophy) and Sinusitis and (Pediatric or Children)". At the end of the evaluation, 36 complete texts were analyzed, 17 of which were considered eligible for the final study, dating from 1997 to 2018. The total population of children assessed in the various studies was of 2371. The studies were categorized as surgical-observational, microbiological, genetic-immunological, and radiological. The analysis of the studies confirms the relationship between AH and CRS and supports the existing consensus on medical and surgical therapy. Furthermore, these studies underline the necessity to adapt medical and surgical treatment considering age, comorbidities including asthma and, if present, the Computed Tomography (CT) score.

The impact of oral appliance therapy with moderate mandibular advancement on obstructive sleep apnea and upper airway volume

Purpose

To find out if a moderate protrusion with a mandibular advancement device (MAD) can significantly increase the upper airway volume and, further, what signs and symptoms of obstructive sleep apnea (OSA) can be improved by this maneuver.

Methods

There were 58 adults diagnosed with OSA who were referred for MAD therapy. The mean apnea-hypopnea index (AHI) was 19.2 (SD 8.6). Five indicators of signs and symptoms of OSA (AHI, oxygen saturation, snoring, daytime sleepiness, and health-related quality of life) were evaluated at the baseline and after 6 months of MAD therapy. Nasal resistance and airway volume and cross-sectional areas with and without the MAD in situ were recorded. Based on AHI reduction, the treatment response was classified as complete, partial, or non-complete. Statistical analyses included the chi-square, t tests, Mann–Whitney U tests, and regression analyses (linear and logistic).

Results

Twenty-three patients attained a complete response (residual AHI < 5 events/h) to MAD therapy. In 13 subjects, the response was partial, and in 9 patients, it was non-complete. The complete responders were significantly younger, and they had a deeper overbite than partial/non-complete responders. A convex profile associated positively, but a vertically restricted throat and increased lower facial height associated negatively with the increase in airway volume.

Conclusions

Excellent MAD therapy outcomes were achieved in most patients. Only age and deep bite had some influence on AHI reduction, indicating multifactorial nature in the response to MAD therapy.

Evaluation of changes in the upper airway after Twin Block treatment in patients with Class II malocclusion

The purpose of this prospective case control study is to describe in growing patients with mandibular hypoplasia, treatment outcomes following functional therapy in terms of volumetric changes in nasopharynx and oropharynx, that is, upper and lower pharynx. We recruited 60 study participants aged between 8 and 12 years having mandibular Class II malocclusion and a reduced upper airway (UA) size, as determined by McNamara cephalometric analyses. Forty patients received Twin Block treatment, whereas the remaining 20 patients did not receive treatment, thus constituting the control group. The control group included patients who did not start treatment after their first visit but returned for a consultation one or 2 years later. All patients underwent an initial teleradiography examination of the skull and a final teleradiography examination to measure changes using McNamara cephalometric analysis of the UA. Pretreatment and posttreatment changes were assessed using Student's t test for independent samples with a significance level of 0.05. Both anatomical structures analyzed-the upper pharynx (nasopharynx) and lower pharynx (oropharynx)-showed significant increases after treatment regardless of whether the patients were boys or girls. The controls showed a decrease in UA size on average after approximately 2 years of growth. A clear relationship exists between the mandibular advancement achieved with TB treatment and an increased UA size. Therefore, the appliance is considered suitable for improving the respiratory quality of growing patients with a decreased UA size.

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.

Comparison of automatic airway analysis function of Invivo5 and Romexis software

Background

Visualization and calculation of the airway dimensions are important because an increase of airway resistance may lead to life-threatening emergencies. The visualization and calculation of the airway are possible using radiography technique with their advance software. The aim of this study was to compare and to test the reliability of the measurement of the upper airway volume and minimum area using airway analysis function in two software.

Methods

The sample consisted of 11 cone-beam computed tomography (CBCT) scans data, evaluated using the Invivo5 (Anatomage) and Romexis (version 3.8.2.R, Planmeca) software which afford image reconstruction, and airway analysis. The measurements were done twice with one week gap between the two measurements. The measurement obtained was analyzed with t-tests and intraclass correlation coefficient (ICC), with confidence intervals (CI) was set at 95%.

Results

From the analysis, the mean reading of volume and minimum area is not significantly different between Invivo5 and Romexis. Excellent intrarater reliability values were found for the both measurement on both software, with ICC values ranging from 0.940 to 0.998.

Discussion

The results suggested that both software can be used in further studies to investigate upper airway, thereby contributing to the diagnosis of upper airway obstructions.

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

Background

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

Objective

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

Search methods

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

Selection criteria

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

Data collection and analysis

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

Results

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

Conclusions

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

Registration

None.

Three-dimensional study of the upper airway in different skeletal Class II malocclusion patterns

OBJECTIVES

To characterize upper airway volume and morphology in patients with different skeletal patterns of Class II malocclusion compared to Class I.

MATERIALS AND METHODS

A total of 197 individuals who had cone-beam computed tomography were allocated into groups according to ANB, SNA, and SNB angles (Class I, Class II maxillary protrusion, Class II mandibular retrusion), each subdivided into hypodivergent, normal, and hyperdivergent. Nasopharynx (NP), oropharynx (OP), and hypopharynx (HP) were assessed with three-dimensional image reconstruction software.

RESULTS

Intergroup comparison did not detect significant differences in volume and morphology of NP, OP, and HP. The males displayed larger OP and HP volume than the females. Positive correlations between age and NP, OP, HP volume and between craniocervical angle and OP and HP volume were observed. Linear regression analysis detected a tendency for OP and HP volume to increase as maxillary and mandibular length increased.

CONCLUSIONS

Upper airway volume and morphology were similar in different skeletal patterns of Class II malocclusion. Actual upper and lower jaw lengths were more closely related to upper airway volume and morphology than the angles that reflected their position relative to the cranial base.

Comparison of the Efficacy, Side Effects, and Cost of Modafinil and Intranasal Mometasone Furoate in Obstructive Sleep Apnea-Hypopnea Syndrome: A Preliminary Clinical Study

Background

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is characterized by repeated episodes of reduction in airflow due to the collapse of the upper airway during sleep. The aim of this study was to compare clinical outcome, side effects, and cost of treatment between modafinil and intranasal mometasone furoate in patients with OSAHS.

Material/Methods

Patients with OSAHS (N=250) were divided into two groups: the modafinil group (MG) (N=125) were treated with 100 mg modafinil twice a day; the intranasal mometasone furoate group (IMFG) (N=125) were treated with 100 μg of intranasal mometasone furoate in the evening. Quality of life, grading of OSAHS, plain-film radiography, the adenoidal-nasopharyngeal ratio (AN ratio), side effects, cost of treatment, and beneficial effects after discontinuation of treatment were evaluated for all patients.

Results

Duration of sleep apnea was significantly reduced in the IMFG compared with the MG (p=0.0145, q=9.262). Modafinil and intranasal mometasone furoate both had moderate effects on improvement of the OSAHS score. The IMFG showed a significantly greater beneficial effect on the AN ratio when compared with the MG (p=0.0001, q=6.584). No adverse events of treatment with modafinil and intranasal mometasone furoate were reported. Cost of treatment and beneficial effect after discontinuation were both significantly greater for the IMFG compared with the MG.

Conclusions

The findings of this preliminary clinical study were that for patients diagnosed with OSAHS, night-time treatment with intranasal mometasone furoate was more effective than modafinil.

Three-Dimensional Imaging in Orthodontics

Orthodontic records are one of the main milestones in orthodontic therapy. Records are essential not only for diagnosis and treatment planning but also for follow-up of the case, communicating with colleagues, and evaluating the treatment outcomes. Recently, two-dimensional (2D) imaging technology, such as cephalometric and panoramic radiographs and photographs, and plaster models were routinely used. However, after the introduction of three-dimensional (3D) technologies (laser scanner, stereophotogrammetry, and computed tomography) into dentistry, 3D imaging systems are more and more commonly preferred than 2D, especially in cases with craniofacial deformities. In fact, 3D imaging provided more detailed and realistic diagnostic information about the craniofacial hard as well as soft tissue and allowed to perform easier, faster, and more reliable 3D analyses. The purpose of this review is to provide an overview of the 3D imaging techniques, including their advantages and disadvantages, and to outline the indications for 3D imaging.

Evaluations of the tongue and hyoid bone positions and pharyngeal airway dimensions after maxillary protraction treatment

OBJECTIVE

To assess changes in the tongue and hyoid bone positions and airway dimensions after maxillary protraction using lateral cephalograms.

METHODS

Lateral cephalograms were obtained before (C0) and after (C1) an observation period for untreated children with skeletal Class I malocclusion and before (T0), immediately after (T1), and one year after (T2) maxillary protraction in children with skeletal Class III malocclusion. Cephalometric measurements were compared between the time points in both patient groups.

RESULTS

Immediately after maxillary protraction, the tongue moved superiorly and the nasopharyngeal and superior oropharyngeal airway dimensions increased. No significant changes in the middle or inferior oropharyngeal airway dimensions or in the hyoid bone position were noted after treatment.

CONCLUSIONS

Maxillary protraction improved tongue posture and modified the nasopharyngeal and superior oropharyngeal airway dimensions in patients with skeletal Class III malocclusion. Consequently, maxillary protraction may restore the intra- and extraoral balance and improve respiratory function.

Correlation and reliability of cone-beam computed tomography nasopharyngeal volumetric and area measurements as determined by commercial software against nasopharyngoscopy-supported diagnosis of adenoid hypertrophy

INTRODUCTION

The aim of this study was to evaluate the diagnostic correlation and reliability of Dolphin Imaging fully automated segmentation (Dolphin Imaging and Management Solutions, Chatsworth, Calif) for assessing adenoid hypertrophy. This was investigated through 3 modes: (1) intraobserver and interobserver agreement of repeated airway auto-segmentation procedures, (2) correlation between auto-segmentation measures of volume and minimal cross-sectional airway against nasopharyngoscopy, and (3) optimum diagnostic cutoff thresholds for volume and minimal cross-sectional airway identified and tested with sensitivity and specificity analyses.

METHODS

Cone-beam computed tomography scans of 38 patients with suspected upper airway obstruction were analyzed. Two calibrated evaluators applied a previously validated method to quantify nasopharyngeal minimal cross-sectional airway and volume using Dolphin Imaging. Assessments were compared against grades of obstruction provided by otolaryngologists' diagnoses.

RESULTS

The reliability between the 2 assessments by the same evaluator on the Dolphin automatic segmentation function for volume (ICC, 0.97; 95% CI, 0.95, 0.98) and minimal cross-sectional airway (ICC, 0.84; 95% CI, 0.69, 0.91) was excellent. The interoperator reliability for volume was also excellent (ICC, 0.97; 95% CI, 0.95, 0.98), but only good (ICC, 0.701; 95% CI, 0.44, 0.85) for minimal cross-sectional airway. In contrast, the Spearman rank correlation test demonstrated weak associations between the values of the automatic measurements for both volume (4.9%; ρ = -0.22) and minimal cross-sectional airway (3.7%; ρ = 0.19). Assessments of accuracy via Receiver Operating characteristic analysis, sensitivity, specificity, negative predictive values, positive predictive values, and likelihood ratios demonstrated the poor clinical applicability of volume and minimal cross-sectional airway numbers provided by Dolphin Imaging.

CONCLUSIONS

The evaluators were reliable at manipulating the selected software, achieving consistent volume and minimal cross-sectional airway measurements, However, Dolphin Imaging volumetric and minimal cross-sectional airway measurements did not correlate well with the nasopharyngoscopy-supported reference standard for adenoid hypertrophy assessment. Under these study conditions, volume and minimal cross-sectional airway used to assess localized adenoid hypertrophy with cone-beam computed tomography imaging based on automated measurements may not yield high-quality clinically relevant information about upper airway constriction related to adenoid hypertrophy.

Cephalometrics of Pharyngeal Airway Space in Lebanese Adults

Purpose. The upper airway space is significant in orthodontic diagnosis and treatment planning. The objectives of this study are to assess the dimensions of soft tissue elements of the upper pharyngeal space and evaluate potential correlations with modifying variables such as gender, skeletal class, and anthropometric parameters. Materials and Methods. Lateral cephalograms were obtained from 117 healthy young adult Lebanese subjects. Nineteen cephalometric linear/angular measurements of the nasopharynx, oropharynx, and hypopharynx were recorded. Anthropometric parameters including body mass index and neck circumference were measured. Results. Significant differences were demonstrated for 12 out of the 19 parameters considered between genders. Uvula and tongue dimensions and the distances between epiglottis-posterior pharyngeal wall and epiglottis-posterior nasal spine were significantly larger in males. The anteroposterior inclination of the uvula and the distances between the uvula and posterior pharyngeal wall were significantly greater in females. No significant differences were found between skeletal classes relative to most of the variables. Body mass index and neck circumference were positively correlated with the dimensions of tongue and uvula. Conclusions. Sexual dimorphism relative to some cephalometric variables and anthropometric parameters may account partly for larger oronasopharyngeal spaces in females. Anthropometric data need to be accounted for in population-related comparisons.

Upper airway changes following single-step or stepwise advancement using the Functional Mandibular Advancer

OBJECTIVES

Purpose of the present study was to determine and compare possible changes in the dimensions of the pharyngeal airway, morphology of the soft palate, and position of the tongue and hyoid bone after single-step or stepwise mandibular advancement using the Functional Mandibular Advancer (FMA).

PATIENTS AND METHODS

The sample included 51 peak-pubertal Class II subjects. In all, 34 patients were allocated to two groups using matched randomization: a single-step mandibular advancement group (SSG) and a stepwise mandibular advancement group (SWG). Both groups were treated with FMA followed by fixed appliance therapy; the remaining 17 subjects who underwent only fixed appliance therapy constituted the control group (CG). The study was conducted using pre- and posttreatment lateral cephalometric radiographs. Data were analyzed by paired t test, one-way analysis of variance, and Pearson's correlation coefficient.

RESULT

In the SWG and SSG, although increases in nasopharyngeal airway dimensions were not significant compared with those in the CG, enlargements in the oropharyngeal airway dimensions at the level of the soft palate tip and behind the tongue, and decreases in soft palate angulation, were significant. Tongue height increased significantly only in the SWG. Compared with the CG, while forward movement of the hyoid was more prominent in SSG and SWG, the change in the vertical movement of the hyoid was not significant. No significant difference between SWG and SSG was observed in pharyngeal airway, soft palate, tongue or hyoid measurements.

CONCLUSIONS

The mode of mandibular advancement in FMA treatment did not significantly affect changes in the pharyngeal airway, soft palate, tongue, and hyoid bone.

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.

Upper airway resistance during growth: A longitudinal study of children from 8 to 17 years of age

OBJECTIVE

To study upper airway breathing in 115 children annually from 8 to 17 years of age with the hypothesis that upper airway respiratory needs increase steadily during growth and show sexual dimorphism.

MATERIAL AND METHODS

To calculate nasal resistance, airflow rate (mL/s) and oronasal pressures (cmH2O) were measured during rest breathing in a seated position using the pressure-flow technique.

RESULTS

Median values of oronasal pressure ranged at different ages in girls from 0.88 to 1.13 and in boys from 0.92 to 1.44 cmH2O, being 0.95 and 0.93 cmH2O at the age of 17 years, respectively. The gender differences were statistically significant in four age groups (P < .05 by the Mann-Whitney test). Mean values of nasal resistance decreased from 8 to 17 years of age in girls from 4.0 (±3.27) to 2.4 (±2.30) and in boys from 3.3 (±2.48) to 1.5 (±0.81) cmH2O/L/s. However, there was an increase in resistance in 11-year-old girls and 12-year-old boys and at the age of 15 in both genders (P < .05 by paired t-test).

CONCLUSIONS

Respiratory efforts stabilize oronasal pressure to maintain vital functions at optimal level. Nasal resistance decreased with age but increased temporarily at the prepubertal and pubertal phases, in accordance with other growth and possibly hormonal changes. When measuring upper airway function for clinical purposes, especially in patients with sleep apnea, asthma, allergies, cleft palate, or maxillary expansion, the measurements need to be compared with age- and gender-specific values obtained from healthy children.