Correlation between the position of hyoid bone and subregions of the pharyngeal airway space in lateral cephalometry and cone beam computed tomography

Cephalometric Evaluation in Patients with Obstructive Sleep Apnea undergoing Lateral Pharyngoplasty

Introduction  Lateral pharyngoplasty (LP) has shown promising results. Craniofacial deformity reduces the pharyngeal space, contributing to the etiopathogenesis. The analysis of craniofacial features can be performed using cephalometry. Objective  To verify if craniofacial deformity is associated with worse polysomnographic data in patients with obstructive sleep apnea (OSA), and to verify if the preoperative cephalometric parameters can interfere with the surgical success of the LP. Methods  The study included 21 patients with OSA aged between 18 and 65 years who underwent LP in a university hospital from 2015 to 2019. Polysomnography was performed postoperatively, after a minimum period of 6 months from the surgical procedure. In addition, a cephalometric evaluation was performed to assess craniofacial deformity, and to correlate it with the polysomnographic results. Results  The mean and median of all polysomnographic respiratory parameters improved postoperatively, especially the apnea-hypopnea index (AHI), which went from 40.15 to 16.60 events per hour ( p  = 0.001). Of the 21 patients, 15 showed improvements in the AHI postoperatively. As for the cephalometric evaluations, we found that the longer the distance between the hyoid bone and the mandibular plane, the greater the patient's preoperative AHI ( p  = 0.011). When assessing whether cephalometric changes related to craniofacial deformities influence the surgical outcome of LP, no correlation was found for any cephalometric measurement. Conclusion  The longer the distance between the hyoid bone and the mandibular plane, the greater the preoperative AHI, and LP was an effective OSA treatment. Cephalometric variables are not able to modify or determine the success of LP in apneic patients in the population assessed.

Oropharyngeal complex differences related to sex and occlusal factors in adolescents aged 12-17 years

OBJECTIVE

To investigate oropharyngeal complex differences related to sex and occlusal factors in adolescents.

METHODS

A cross-sectional study was conducted with 108 patients aged 12-17 years. The oropharyngeal complex was evaluated by imaging exams. Occlusal variables included molar relationship, facial growth pattern, maxilla shape, tooth loss, anterior crossbite, and anterior open bite. Statistical analysis included independent t-test, Mann-Whitney, ANOVA, and Kruskal-Wallis tests. The significance level was 5%.

RESULTS

There were increases of the tongue measurement (p = 0.026) and the hyoid approach at the base of the mandible among boys (p = 0.016) and the distance from the hyoid at the base of the mandible among girls (p = 0.039). There was shortening of the soft palate measurements (p = 0.003 and p = 0.007) and tongue (p = 0.018) among adolescents with an anterior crossbite.

CONCLUSION

Findings suggest sex, age, and anterior crossbite can be related to oropharyngeal morphology.

Comparison of invisalign mandibular advancement and twin-block on upper airway and hyoid bone position improvements for skeletal class II children: a retrospective study

BACKGROUND

This study is to evaluate and compare the improvement of upper airway morphology and hyoid bone position in children with Class II mandibular retrusion treated with Invisalign mandibular advancement (MA) and Twin-Block (TB) appliances, utilizing cone beam computed tomography (CBCT).

METHODS

32 children aged between 8 and 11.5 years old were included in this study, with an average age of 10.2 years old. These children were divided into two groups, MA and TB, with 16 children in each group. Changes in upper airway morphology and hyoid bone position before and after treatment were analyzed using CBCT.

RESULTS

(1) Changes in upper airway before and after treatment: the oropharynx volume (Or-V), the oropharynx minimum cross-sectional area (Or-mCSA), the hypopharynx volume (Hy-V), and the hypopharynx minimum cross-sectional area (Hy-mCSA) in both the MA and TB groups increased after treatment, and the differences were statistically significant (P < 0.05) compared to pre-treatment status. (2) Changes in hyoid bone position before and after treatment: The distances between H point and third cervical vertebra (H-C3), H point and pogonion (H-RGN), H point and mandibular plane (H-MP), H point and Frankfort horizontal plane (H-FH), H and S point (H-S), and H point and palatal plane (H-PP) in both the MA and TB groups increased after treatment, and the differences were statistically significant (P < 0.05).

CONCLUSION

Both MA and TB appliances effectively improved the structural narrowness of the upper airway and reduced respiratory resistance, thus improving breath quality. However, MA showed more effectiveness in improving the narrowest part of the hypopharynx compared to TB. Both appliances also promoted anterior downward movement of the hyoid bone, which opens the upper airway of the oropharynx and hypopharynx and helps the upper airway morphology return to normal range.

Multi-stage Unet segmentation and automatic measurement of pharyngeal airway based on lateral cephalograms

OBJECTIVES

Orthodontic treatment profoundly impact the pharyngeal airway (PA) of patients. Airway examination is an integral part of daily orthodontic diagnosis, and lateral cephalograms (LC) are reliable to reveal PA structures. This study attempted to develop a simple method to help clinicians make a preliminary judgement of patients' PA conditions and assess the impact of orthodontic treatment on their airways.

METHODS

LCs of 764 patients were used to train a multistage unit segmentation model. Another 130 images were used to validate the model and more 130 images were used to test the model.

RESULTS

Unet was used as the backbone, with a mean dice value of 0.8180, precision of 0.8393, and recall of 0.8188. Furthermore, we identified seven key points and measured related indices. The length of the line separating the nasopharynx and oropharynx and the line separating the oropharynx and hypopharynx were manually measured thrice and the average values was compared. The intraclass correlation coefficient (ICC) for the two lines was 0.599 and 0.855. Then, we performed a single linear regression analysis, which indicated a strong correlation between the predictions and measurements for the two lines.

CONCLUSIONS

This method is reliable for segmenting three regions (nasopharynx, oropharynx, and hypopharynx) of the PA and calculating related indices. However, the predictions obtained from this model still have errors, and it is necessary for clinical practitioners to assess and adjust the predictions.

CLINICAL SIGNIFICANCE

Our model can help orthodontists formulate personalised treatment plans and evaluate the risk of airway stenosis during orthodontic treatment. This method may mark the beginning of a new and simpler approach for PA obstruction detection, specifically tailored to orthodontic patients.

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).

Assessment of posterior tilting of the hyoid bone in relation to carotid atherosclerosis: a CBCT study

Aim: The present study aimed to investigate whether the presence and areal and volumetric measurements of the unilateral extra-cranial carotid artery calcifications (ECACs) are associated with posterior tilting of the hyoid bone. Material and Method: A total of 658 cone-beam computed tomography (CBCT) scans were screened for the presence of ECACs. The calcifications were categorized as unilateral (right or left) or bilateral. Study group was consisted of cases with unilateral ECACs. A control group without ECACs matching with study group by age and gender was created. Volumetric and areal measurements in the ECAC group were done by using Mimics Medical software. Posterior tilting of the hyoid bone in relation to mid-sagittal plane and the dimension of posterior inclination through the greater horns were measured on i-Cat Vision software. Results: In total, 71 (10.8%) ECACs (30 bilateral and 41 unilateral) were detected. Study group consisted of 41 (6.2%) unilateral ECAC cases [25 (61%) females and 16 (39%) males]. Gender and age distributions were similar between ECAC and control groups. No significant difference between two groups was found considering the prevalence of posterior tilting of the hyoid bone (63.4% vs. 43.9%, p=0.240). Similarly, there was no significant difference in the mean dimension of posterior inclination between groups (2.48±2.12 mm. vs. 2.24±1.47 mm, p=0.646). The volume and areal measurements of calcifications were not correlated with the dimension of posterior inclination of the hyoid bone. Conclusion: Posterior tilting of the hyoid bone may be a frequent finding in cases of unilateral ECAC. However, the present findings suggest that no significant relationship exists between the presence of unilateral ECACs and posterior tilting of the hyoid bone.

Oropharynx and hyoid bone changes in female extraction patients with distinct sagittal and vertical skeletal patterns: a retrospective study

Background

Previous studies have reported inconsistent effects of premolar extraction on the oropharynx and hyoid bones. Currently, no strong evidence is available regarding the effect of extraction on upper airway size. Hence, the aim of this study was to analyse the effects of first premolar extraction on the oropharynx and hyoid bone positions in female adult patients, and further explored differences in oropharynx and hyoid bone changes among skeletal patterns.

Methods

The study population included 40 female adult patients who did not undergo extraction and 120 female adult patients who underwent extraction of four premolars; the including patients had four distinct sagittal and vertical skeletal patterns. Cone-beam computed tomography was performed before (T0) and after (T1) orthodontic treatment. Eight oropharynx variables and five hyoid bone variables were measured using Dolphin 3D Imaging software. Paired and independent t-tests were used to analyse measurements between timepoints and groups, respectively.

Results

The oropharynx volume increased significantly in the extraction group; changes did not differ significantly between extraction and non-extraction groups. Oropharynx variables did not differ significantly at T0 among the four skeletal pattern groups. After orthodontic extraction treatment, the oropharynx volume increased significantly in the class I-norm and class I-hyper subgroups, but not in the class II-norm and class II-hyper subgroups. Significant increases were observed in the oropharynx volume and most constricted axial area from T0 to T1 in the moderate retraction group, but not in the maximum retraction group. Extraction patients exhibited significant posterior movement of the hyoid, particularly among maximum retraction patients.

Conclusions

In female adult patients, first premolar extraction tends to increase the oropharynx size and cause posterior movement of the hyoid bone, particularly in skeletal class I patients. For skeletal class II and hyperdivergent patients with a narrow oropharynx, first premolar extraction does not negatively influence oropharynx size or hyoid bone position. The differences of oropharyngeal changes between moderate retraction patients and maximum retraction patients were not significant.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13005-022-00334-1.

Effects of mandibular distraction osteogenesis on anesthetic implications in children with hemifacial microsomia

BACKGROUND

Hemifacial microsomia (HFM) is a congenital craniofacial malformation, and its features include hypoplasia and asymmetry in skeletal tissue and soft tissue. These features are usually associated with a difficult airway. Mandibular distraction osteogenesis can achieve mandibular advancement, but its effect on the subsequent laryngoscopic views has not been adequately documented.

AIM

The aim of this study was to determine the change in laryngoscopic views after mandibular distraction osteogenesis (MDO) in children with HFM and to examine the radiological changes after MDO by using computed tomography (CT)-based three-dimensional (3-D) airway reconstruction.

METHODS

An observational prospective study was carried out in children with HFM undergoing MDO. All children underwent 3-D airway reconstruction preoperatively before the placement and removal of the distractor. The temporomandibular joint lesions in children were classified by the Pruzansky-Kaban classification. The Cormack-Lehane grade was assessed after induction under direct laryngoscopy. The relationship between difficult laryngoscopy and the Pruzansky-Kaban classification was assessed. Changes in the upper pharyngeal airway parameters and laryngoscopic views were analyzed.

RESULTS

Forty children (ages ranging from 5 to 16 years, males = 26, females = 14) with HFM underwent 80 anesthesia for MDO. The incidence of difficult laryngoscopy before mandibular distraction was 5/12 (41.7%) in type IIa, 19/24 (79.2%) in type IIb and 1/4 (25%) in type III HFM. The mean difference in the incidence of difficult laryngoscopy before and after MDO was 33.3% (95% CI: -6.7% to 73.3%), 50.0% (95% CI: 8.4% to 91.6%), and 0% for type IIa, type IIb, and type III, respectively. In type IIb, 12/19 cases of difficult laryngoscopy became easy after mandibular distraction: this was associated with an increase in the palatopharyngeal and glossopharyngeal CT parameters (p < .05). In type IIa, 5/5 cases of difficult laryngoscopy became easy after mandibular distraction, and 1/7 cases of easy laryngoscopy became difficult laryngoscopy. However, there were no significant changes in the palatopharyngeal, glossopharyngeal, and hypopharyngeal CT parameters in type IIa and type III HFM (p > .05).

CONCLUSIONS

MDO can improve the laryngoscopic views in children with HFM. According to the Pruzansky-Kaban classification, children with type IIb showed the highest incidence of difficult laryngoscopy before MDO. After MDO, the improvement in laryngoscopic views under direct laryngoscopy in type IIb was related to the increase in the palatopharyngeal and glossopharyngeal volume.

Do the dimensions of the hard palate have a relationship with the volumes of the upper airways and maxillary sinuses? A CBCT study

Background

As the hard palate is a central structure of the skull, and its close relationship with the nasal cavity, oral cavity, and maxillary sinuses, it would be of interest to study if there is a relationship between this bone and other structures of the stomatognathic system. Thus, this study aimed to assess the dimensions of the hard palate and associate them with sex, and skeletal and breathing patterns. Also, to investigate if there is a relationship between these dimensions and the volumes of the upper airways and maxillary sinuses.

Methods

Two hundred and ninety-eight CBCT scans of patients were classified according to sex, and skeletal and breathing patterns. Then, the linear dimensions of width and height of the hard palate at the regions of the first premolars and first molars, and the volumes of the upper airways and maxillary sinuses were measured using the CS 3D Imaging and ITK-SNAP software, respectively. Data were submitted to multi-way analysis of variance and linear regression, with a significance level of 5% (α = 0.05).

Results

Sex and facial type influenced the hard palate dimensions (p < 0.05). Males had greater width and height of the hard palate than females (p < 0.0001). It was observed greater width for brachycephalics at the first premolars region (p = 0.0032), and greater height for dolichocephalics at the first premolars (p = 0.0154) and first molars (p = 0.0038) regions. Skeletal malocclusion and breathing pattern did not influence the measurements of the hard palate (p > 0.05). There was a significant relationship between the width and height of the hard palate at the premolar’s region and the total volume of the upper airways (p = 0.018, and p = 0.038), and between both dimensions of the hard palate at the molar’s region and the total volume of the maxillary sinuses (p < 0.0001).

Conclusions

The hard palate dimensions are influenced by sex and facial type, but not by skeletal malocclusion or breathing pattern. Also, there is an association between these dimensions and the volumes of the upper airways and maxillary sinuses.

Pharyngeal Airway Space Dimensions and Hyoid Bone Position in Various Craniofacial Morphologies

Objective:

To assess the relationship of pharyngeal airway dimensions and the position of the hyoid bone in several craniofacial morphologies among Nepali adults. To assess the relationship between dimensions of the pharyngeal airway and position of the hyoid bone and compare gender dimorphism.

Materials and Methods:

The cross-sectional observational research comprised lateral cephalograms of 150 subjects aged 16 to 30 years. Samples were separated into three sagittal craniofacial morphological groups based on the ANB (A point, nasion, B point) angle and into gender groups. Different parameters (linear and angular) for measuring dimensions of the pharyngeal airway and position of the hyoid bone were assessed. An ANOVA test and a Pearson correlation test were performed.

Results:

Dimensions of the pharyngeal airway were largest in skeletal Class III when compared to skeletal Class I and Class II subjects, with a lower pharyngeal airway space and the length of the nasal fossa being significantly larger. The hyoid bone was anteriorly and inferiorly placed in Class III skeletal subjects. Males had greater pharyngeal airway dimensions and a hyoid bone positioned more inferiorly and anteriorly. The nasal fossa length had a strong positive correlation with the hyoid bone position vertically.

Conclusion:

There were differences in the dimensions of the pharyngeal airway and position of the hyoid bone in various craniofacial morphologies among Nepali adults. Gender dimorphism was observed in both dimensions of the pharyngeal airway and the position of the hyoid bone.

Study of Upper Pharyngeal Airway Dimension in Young Adults Visiting Orthodontic Department of a Dental College: A Descriptive Cross-sectional Study

Introduction:

Orthodontic treatment may affect the size and position of oropharyngeal structures altering the airway dimension. Airway dimension is considered as one of the parameter of orthodontic diagnosis and treatment planning. Narrow airway passage is associated with sleep disordered breathing. This aims to study about the measurement of upper pharyngeal airway dimension of young Nepalese adults visiting orthodontic department of a dental college.

Methods:

This descriptive cross-sectional study conducted at Department of Orthodontics, People's Dental College and Hospital, Kathmandu. Data was collected from 8^th December 2020 to 28^th February 2021. Ethical clearance (Reference number. 1, CH100 06, 2077/2076) was taken from Institutional Review Committee of Peoples Dental College and Hospital, Kathmandu, Nepal. Convenient Sampling technique was done. Data was collected and analysis was done using Statistical Package of Social Sciences 16.

Results:

Mean upper pharyngeal airway dimension was 11.40±1.84mm and 11.68±1.96mm for male and female respectively. Upper pharyngeal airway dimension was found to be almost similar for male and female.

Conclusions:

Gender diversity regarding upper pharyngeal airway dimesnion was not observed in this study while other studies also revealed similarities in upper pharyngeal airway dimension between male and female, inspite of larger craniofacial dimension in males than females.

A cross-sectional retrospective study of normal changes in the pharyngeal airway volume in white children with different skeletal patterns. Part 2: Cervical vertebral maturation method and hyoid bone

INTRODUCTION

The purpose of this cross-sectional retrospective study was to evaluate the patterns of pharyngeal airway volume change determined by cervical vertebral maturation (CVM) stage and compare it with that which was characterized by chronological age. Correlations between hyoid bone positions and airway volumes were also examined.

METHODS

CVM staging was determined from cone-beam computed tomography scans of 420 white patients aged 9-15 years. Patients were stratified on the basis of sex and skeletal pattern to establish pharyngeal airway volume clusters for each CVM stage. The horizontal and vertical positions of hyoid bones were measured using Hyoidius and Sella.

RESULTS

Males had larger pharyngeal airway volumes compared with females. In males, the largest increases in pharyngeal airway volumes occurred at an earlier CVM stage than females. No statistically significant differences in pharyngeal airway volumes were noted in subjects with skeletal Class I, II, and III malocclusion. The hyoid bone in males was more anteriorly and inferiorly positioned compared with females. The Class III group had a further forward position of the hyoid bone than the Class I and II groups.

CONCLUSIONS

The patterns of pharyngeal airway change obtained using CVM staging did not correlate well with traditional maturational models for skeletal growth. It implies that chronologic age could be a relatively reliable indicator for the assessment of pharyngeal airway volumes in adolescents, as outlined in part 1 of the present study. Subjects with anteriorly and superiorly positioned hyoid bones exhibited smaller pharyngeal airway volumes, which highlights the role of soft tissue and its influence on airway patency.

Correlation between craniofacial structures, anthropometric measurements, and nasopharyngeal dimensions in black adolescents

OBJECTIVES

To evaluate the correlation between craniofacial structures, anthropometric measurements, and bony and soft tissue nasopharyngeal dimensions in African Black adolescents.

METHODS

This retrospective cross-sectional study was conducted on 483 healthy adolescents (250 females and 233 males), randomly selected from one dental clinic. The inclusion criteria were skeletal and dental Class I, Black ethnicity, pubertal growth period as determined by the Greulich and Pyle atlas criteria, and no history of orthodontic treatment. Anthropometric measurements (stature, upper body height, lower body height, and BMI) and radiographic records (hand-wrist radiographs, and lateral cephalograms) were obtained. One investigator traced and analysed all cephalograms to determine three skeletal craniofacial parameters (maxillary length [Ar- ANS], mandibular length [Ar-Gn], and lower anterior facial height [ANS-Me]), and 14 (8 skeletal and 6 soft tissue) nasopharyngeal parameters. Pearson correlation coefficients and stepwise multiple linear regression analyses were conducted.

RESULTS

The mean skeletal ages of females and males were 11.31±2.31y and 12.66±1.85y, respectively. Multiple linear regression analyses showed that stature, posterior height of nasal cavity (S-PNS), length of nasal floor (AA-PNS), and mean area of bony nasopharynx (Area 1) were significantly correlated with maxillary length, P<.001. Stature, BMI, S-PNS, vertical angle of nasopharynx (Ba-S-PNS), Area 1, adenoid height (AD), and linear hyoid bone measurements (H-AA, H-RGN, H-Ax) were all correlated with mandibular length, P<.05. Lower facial height showed sexual dimorphism and was significantly associated with vertical nasopharyngeal measurements, BMI and upper body height.

CONCLUSIONS

Craniofacial structures were significantly associated with stature and upper body height. Maxillary growth was associated with bony nasopharyngeal variables. Mandibular growth and lower facial height were associated with bony and soft tissue nasopharyngeal variables. The sexual dimorphism in lower facial height warrants future studies to fully understand and manage the craniofacial complex and nasopharyngeal airway in African Black adolescents.

Changes of epiglottis and hyoid bone position after orthodontic treatment with cast splint fixed functional appliances

OBJECTIVES

Angle Class II malocclusions including a retrognathic mandible are the most frequent orthodontic problems. Both removable and fixed functional appliances can be used for mandibular advancement. Mandibular advancement after treatment with any fixed functional appliance has numerous therapeutic effects, such as stretching of masticatory muscles, ligaments, membranes and surrounding soft tissues, thus causing positional changes of the hyoid bone and epiglottis. This retrospective study investigates and compares treatment effects upon epiglottis- and hyoid bone position and posterior airway space in class II patients who received mandibular advancement through two different cast splint fixed functional appliances.

MATERIAL AND METHODS

Two groups of 21 patients each ('Functional Mandibular Advancer' (FMA) and Herbst appliance) were investigated. The same experienced orthodontist performed the treatment in all patients, employing a single-step advancement protocol. The mandible always received initial protrusion into an edge-to-edge position. Conventional lateral cephalograms were available pre-treatment (T1) and immediately after appliance removal (T2) for all patients. The measurements comprised (I) hyoid bone, (II) epiglottis or (III) posterior airway space. Treatment-related changes were analysed with one-sample Student's t tests for intragroup comparisons and independent Student's t tests for intergroup comparisons. Statistical significance was set at p < 0.05.

RESULTS

Measurements of the hyoid bone showed mostly increases for both appliances after treatment. Intergroup comparisons were not significant for FMA patients but significant for selected measurements in Herbst appliance patients. Intergroup comparisons showed insignificant changes. The posterior airway space was always insignificantly increased after treatment. The greatest increase was found caudally. Intergroup comparisons showed insignificant changes.

CONCLUSIONS

Both fixed functional appliances cause an anterior and caudal displacement of epiglottis and hyoid bone and enlarge the posterior airway space. The therapeutic effects of the Herbst appliance are slightly larger, although not significantly.

CLINICAL RELEVANCE

Treatment with either Herbst appliance of FMA alters the hyoid bone position and enlarges the posterior airway space. Still, long-term data are as yet unavailable; it remains unknown if the effects upon posterior airway space remain stable, and if a resulting posterior airway space enlargement may have clinical influence upon obstructive sleep apnoea syndrome.