A three dimensional study of upper airway in adult skeletal Class II patients with different vertical growth patterns

Assessment of maximal inspiratory and expiratory pressures in skeletal Class II patients with different growth patterns

OBJECTIVES

To evaluate maximal inspiratory (MIP) and expiratory (MEP) pressures, which are reflective of respiratory muscle strength, in skeletal Class II patients with different growth patterns (horizontal, average, and vertical) and to correlate those with airway dimension.

MATERIALS AND METHODS

Patients with a Class II skeletal base seeking orthodontic treatment were assigned to the following groups: average, horizontal, and vertical growth pattern. The control group (n = 14) comprised patients with a Class I skeletal base and average growth pattern. Airway dimensions were obtained using cone-beam computed tomography scans, and a spirometer with a pressure transducer was used for assessment of MIP and MEP. Routine spirometry for assessment of lung function was also performed.

RESULTS

No significant differences were found in maximal inspiratory and expiratory pressures for the study groups in comparison with the control group. Class I patients had significantly greater oropharyngeal and nasopharyngeal airway volumes compared with the study groups. No significant difference in minimal cross-section area of the airway was observed among groups. A weak positive correlation between maximal inspiratory pressure and airway volume was observed.

CONCLUSIONS

Although Class I patients displayed significantly greater oropharyngeal and nasopharyngeal airway volumes, there was no significant difference in respiratory muscle strength or airway function between Class II patients with different growth patterns and the Class I control group. The findings underscore the significance of exploring factors beyond craniofacial growth patterns that may contribute to sleep-related breathing disorders.

Correlation between craniocervical posture and upper airway dimension in patients with bilateral anterior disc displacement

OBJECTIVE

To investigate the relationship between upper airway dimension and craniocervical posture in adult patients with bilateral anterior disc displacement and to provide some references for clinical diagnosis and plan formulation in orthodontics.

METHODS

Based on RDC/TMD (Research Diagnostic Criteria for Temporomandibular Disorder), 98 Patients were divided into three groups by two experienced TMJ (Temporomandibular Joint) specialists: bilateral disc normal position group (BN), bilateral anterior disc displacement with reduction group (ADDWR) and bilateral anterior disc displacement without reduction group (ADDWoR). Inter-group comparison and correlation analysis were performed after 11 craniocervical posture and 15 upper airway dimension measurements finished with Dolphin and Uceph software in Two or Three-dimensional.

RESULTS

Anterior disc displacement often accompanied with extension of craniocervical posture, as ADDWR and ADDWoR groups have significantly higher cervical curvature and inclination than BN group (P < 0.05). Simultaneously anterior disc displacement often associated with constrained upper airway dimension for the total and each segment upper airway volume were significantly smaller in ADDWR and ADDWoR than BN group (P < 0.05). Correlation analysis revealed that C0-C1 (the distance from the base of the occipital bone (C0) to the posterior arch of the atlas (C1)) is significantly related to the total and each segment upper airway volume reduction (P < 0.05).

CONCLUSION

There exists markedly close correlation between anterior disc displacement and craniocervical posture forward extension, which may be physiologically adaptive cervical extension to keep oropharyngeal airway unobstructed as upper airway dimension constrained by anterior disc displacement.

CLINICAL RELEVANCE

These findings allow us to infer the potential consequences if the treatment of anterior disc displacement would result in an improvement of intervertebral relationships and upper airway constraint.

Prediction of Pharyngeal 3D Volume Using 2D Lateral Area Measurements During Swallowing

This study evaluated the validity of pharyngeal 2D area measurements acquired from the lateral view for predicting the actual 3D volume in healthy adults during swallowing. Seventy-five healthy adults (39 females, 36 males; mean age 51.3 years) were examined using 320-row area detector computed tomography (320-ADCT). All participants swallowed a 10 mL honey-thick barium bolus upon command while seated in a 45° semi-reclining position. Multi-planar reconstruction images and dynamic 3D-CT images were obtained using Aquilion ONE software. Pharyngeal 2D area and 3D volume measurements were taken before swallowing and at the frame depicting maximum pharyngeal constriction. Pharyngeal volume before swallowing (PVhold) was accurately predicted by 2D area (R2 = 0.816). Adding height and sex to the model increased R2 to 0.836. Regarding pharyngeal volume during maximum constriction (PVmax), 2D area also exhibited acceptable predictive power (R2 = 0.777). However, analysis of statistical residuals and outliers revealed a greater tendency for prediction errors when there is less complete constriction of the pharynx as well as asymmetry in bolus flow or movement. Findings highlight the importance of routinely incorporating anterior-posterior views during VFSS exams. Future work is needed to determine clinical utility of pharyngeal volume measurements derived from 320-ADCT.

Three-dimensional assessment of Upper Airway in Class III patients with different facial patterns

Background

To evaluate three-dimensionally the upper airway (UA) of class III adults with different facial patterns.

Material and Methods

A cross-sectional study was conducted, in which cone-beam computed tomography (CBCT) images from a private clinic in Viña del Mar, Chile were evaluated. The sample consisted of CBCT images of 59 skeletal class III subjects (33 females and 26 males, mean age 24.7 years) in which the vertical facial pattern was determined using the Vert index, and the minimum cross-sectional area and total volume of the UA were measured. The minimum cross-sectional area variable was analyzed by ANOVA and the total volume was analyzed by Kruskal-Wallis test. Statistical analyses were performed with JASP 0.13.1 software at p=0.05.

Results

The sample included images of 21 brachyfacial, 14 mesofacial and 24 dolichofacial subjects. The mean minimum cross-sectional area of the sample was 591.78 mm2 +/- 149.38 mm2 (minimum=352.00 mm2; maximum=971.00 mm2), being greater in brachyfacial than in dolichofacial and mesofacial subjects, however, these differences were not significant (p=0.147). The mean total volume of the sample was 13.40 +/- 4.69 cm3 (minimum=7.16 cm3; maximum=25.66 cm3), being greater in brachyfacial than in dolichofacial and mesofacial subjects, however, these differences were not significant (p=0.353).

Conclusions

Considering the limitations of the present study, the vertical facial pattern does not appear to significantly influence upper airway measurements in skeletal class III adults. Key words:Airway, cephalometry, cone-beam computed tomography, facial pattern, malocclusion, Angle class III.

Pharyngeal airway dimensions in Iranian female young adults with different skeletal patterns using cone-beam computed tomography

OBJECTIVES

To assess the oropharyngeal airway in Iranian female young adults with different skeletal patterns using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This descriptive, cross-sectional study evaluated 105 CBCT scans of female patients between 18 and 35 years retrieved from the archives of a radiology clinic. The images were evaluated in axial, sagittal, and frontal sections. In the axial plane, the maximum and minimum cross-sectional area (CSA) of the airways at the oropharynx, minimum width (anteroposteriorly), and minimum depth (laterally) were measured using Mimics Medical software. The oropharyngeal volume was measured by NemoFAB software. The values were compared among the groups with different sagittal, vertical, and transverse patterns. The correlation of indices with airway measurements was analyzed using Monte Carlo Chi-square and Pearson's correlation coefficient.

RESULTS

No significant difference was noted in oropharyngeal airway dimensions and volume among cases with different skeletal sagittal, vertical, and transverse patterns (P > 0.05) except for class III patients with normal transverse pattern in whom maximum CSA in low-angle group was larger than that in normal-angle group (P < 0.05) and class I normal-angle patients in whom maximum CSA in transverse normal group was smaller than that in constriction group (P < 0.05).

CONCLUSIONS

Oropharyngeal dimensions were not significantly different in Iranian female young adults with different skeletal patterns.

Correlation between the three-dimensional maxillomandibular complex parameters and pharyngeal airway dimensions in different sagittal and vertical malocclusions

OBJECTIVES

This study aimed to determine the three-dimensional (3D) correlation between maxillomandibular complex parameters and pharyngeal airway dimensions in different sagittal and vertical malocclusions.

METHODS

This retrospective cross-sectional study included the CBCT scans of 368 patients with a mean age of 23.81 ± 3.01 years. The patients were classified into three groups (skeletal Class I, II, and III). Each class group was divided into three subgroups based on vertical growth patterns (hypo-, normo-, and hyperdivergent). The maxillomandibular complex was evaluated in the three planes using 16 skeletal measurements. Naso-, oro-, hypo-, and total pharyngeal airway spaces were assessed in terms of width, volume, surface area, and minimum constricted area (MCA). Two-way ANOVA followed by the Bonferroni post-hoc test were used.

RESULTS

The nasopharyngeal airway space was significantly lowest regarding sagittal and lateral widths in the skeletal Class III patients, the lowest volume and surface area were in hyperdivergent patients, and MCA was the highest in Class II and hypodivergent patients. The oro- and hypopharyngeal sagittal width, volume, surface area, and MCA were the lowest in the hyperdivergent patients, and oropharyngeal lateral width and hypopharyngeal sagittal width were the highest in skeletal Class III. The total pharyngeal volume, surface area, and MCA were the lowest in the hyperdivergent patients, and skeletal Class II patients had the lowest MCA.

CONCLUSIONS

The pharyngeal airway dimensions differ with various sagittal and vertical malocclusions. These differences could apply to diagnosis, treatment planning, and possible changes following orthodontic/orthopedic or surgical treatment.

The effect of orthodontic vertical control on the changes in the upper airway size and tongue and hyoid position in adult patients with hyperdivergent skeletal class II

BACKGROUND

At present, there are still controversies about the influence of orthodontic treatment on the size of upper airway and the position of hyoid bone. We investigated the effect of orthodontic vertical control therapy on the size of the upper airway and position of the tongue and hyoid bone in adult patients with hyperdivergent skeletal Class II.

METHODS

Overall, 15 adults with hyperdivergent skeletal Class II and normal occlusion, respectively, were selected as the experimental and control groups. The angle and line of the craniofacial structure, upper airway, hyoid bone position and three-dimensional (3D) upper airway indexes were measured using the Uceph 4.2.1 standard version and Mimics 21.0 software, respectively. The paired t-test, Wilcoxon symbol rank test, t-test of two independent samples, two independent sample nonparametric tests, Mann-Whitney U test, Pearson correlation analysis, the Univariate linear regression analysis and Multiple linear regression analysis were performed.

RESULTS

After treatment, the S-Go/N-Me (%) and the MP-SN and XiPm-SN angles were significantly different (P < 0.01). The U-MPW and PAS significantly increased (P < 0.05), sagittal diameter L₂ increased significantly, and transverse diameter L₂ decreased significantly (P < 0.01). Although no significant correlation was observed between the vertical change in the jaw and that in U-MPW and PAS, the sagittal diameter L₂ showed a significant correlation (P < 0.05). The Multiple linear regression analysis showed that there was a significant negative correlation between the variables MP-SN and sagittal diameter L₂ and positive correlation between S-Go/N-Me(%) and H-MP (P < 0.05). Furthermore, significant differences between the Hv (P < 0.01) and sagittal diameter L₁(P < 0.05) were observed before and after treatment.

CONCLUSIONS

After the orthodontic vertical control therapy in patients with hyperdivergent skeletal Class II, the upper airway only underwent adaptive changes during treatment without substantial size changes, the position of tongue body and hyoid bone did not change significantly. Furthermore, compared with normal occlusion, the velopharyngeal segment airway of patients with hyperdivergent skeletal Class II remains narrow and long after treatment.

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.

[Dimensions of the upper airways and its impact on the dentoalveolar system development]

Due to the high mobility and variability of bone structures and soft tissues surrounding the upper respiratory tract, the exact boundaries for measuring and normalizing the size of the respiratory tract have not yet been determined. Studies have determined the relationship between the narrowing of the upper jaw and a decrease in the transverse dimensions of the airways, as well as a positive effect in changing the size of the airways after orthodontic treatment and/or orthognathic surgery. Nevertheless, the results of research in this area may differ greatly from different specialists, which indicates that the topic is poorly studied and it is necessary to continue and expand the range of scientific works to assess the state of the upper respiratory tract and their relationship with the orthodontic status.

Validation of manufacturers' laryngeal mask airway size selection standard: a large retrospective study

Background

Laryngeal mask airway (LMA) is a prominent supraglottic airway device, widely used especially in difficult airway management. However, the LMA sizes recommended by the manufacturers are not always well matched in clinical practice, which leads to complications. To date, there are rare models to validate whether the manufacturers’ standard is suitable for use in clinical practice.

Methods

A total of 58,956 patients undergoing general anesthesia using LMA device were included in the study between January 1, 2011 and December 31, 2018, to validate the adherence rate of LMA sizes according to the manufacturers’ recommendations. A logistic regression analysis was performed based on the actual LMA size used in clinical practice to establish separately size selection guidelines with gender, weight, and age as variables in adults, adolescents, and children.

Results

LMA insertions were analyzed in 50,776 (86.1%) adults, 3,548 (6%) adolescents, and 4,632 (7.9%) children. Suitability of manufacturers’ recommendations was higher in children [male: 86.02%; female: 85.09%] than adults [male: 72.75%; female: 78.13%] or adolescents [male: 73.4%; female: 70.79%]. For adults and adolescents, LMA size was better predicted using the regression model rather than the manufacturers’ recommendations [male adults: 82.4% (81.16–83.57%) vs. 73.21% (71.79–74.59%), P<0.05; female adults: 87.82% (86.65–88.9%) vs. 77.07% (75.6–78.48%), P<0.05; male adolescents: 79.45% (74.86–83.4%) vs. 72.05% (67.09–76.53%), P<0.05; female adolescents: 78.4% (71.11–84.31%) vs. 72.22% (64.54–78.82%), P<0.05]. For children, there was equal performance suitability using the regression model and the manufacturers’ recommendations.

Conclusions

The model-based guidelines may provide more accurate directions for LMA size selection for adolescents and adults than the manufacturers’ weight-based recommendations, whereas the manufacturers’ recommendation in children is consistent with clinical practice.

Evaluation of pharyngeal airway dimensions and hyoid bone position according to craniofacial growth pattern

OBJECTIVE

To compare pharyngeal airway dimensions and hyoid bone position in different craniofacial growth patterns.

METHODS

In total, 611 patients divided into 9 subgroups were compared according to malocclusion classification and vertical growth pattern, and these subgroups were compared in terms of pharyngeal airway and hyoid measurements. A two-way ANOVA test was used to compare the findings of the subgroups.

RESULTS

No significant difference was found for the pharyngeal measurements between the groups (p>0.05). The vertical airway length (PNS-Ep) was significantly shorter in the Class III malocclusion group (p<0.05) and in the hypodivergent group (p<0.05). No statistically significant difference was found between any subgroups in any measurements of the position of the hyoid bone (p>0.05).

CONCLUSION

The pharyngeal airway dimensions and hyoid bone position are similar among individuals in the sagittal direction. The vertical airway length is significantly shorter in Class III and hypodivergent individuals.

Effects of clear aligner therapy for Class II malocclusion on upper airway morphology and daytime sleepiness in adults: A case series

INTRODUCTION

To evaluate the effects of clear aligner therapy (CAT) on the upper airway dimensions and on daytime sleepiness in adults with dentoskeletal Class II malocclusion.

METHODS

This study was conducted from August 2017 to February 2019. Inclusion criteria were healthy adults≥18years old, Angle Class II division 1 malocclusion, first-molar relationship of end-to-end or greater, overjet<10mm, and presenting for multi-arch comprehensive orthodontic treatment with aligners. Treatment mechanics included mandibular dentoalveolar advancement with Class II elastics without maxillary sequential distalization programmed into aligners. Post-treatment changes in dentoskeletal and upper airway dimensions were assessed using CBCT images. The treatment effect on daytime sleepiness was evaluated using an Epworth Sleepiness Scale (ESS).

RESULTS

Eight subjects were included in this pilot study (mean age at treatment initiation=44.6years [SD=15.3]). The mean treatment duration was 12.2months (SD=3.4). No statistically significant treatment changes were observed in upper airway dimensions or dentoskeletal cephalometric analyses. Subjects with excessive daytime sleepiness at pre-treatment reported an improvement post-treatment, but no significant difference in the mean ESS score was found.

CONCLUSION

Treatment of Class II division 1 malocclusion in adults by mandibular dentoalveolar advancement using CAT has no statistically significant effects on the airway and dentoskeletal measurements, or daytime sleepiness.

Three-Dimensional Upper Airway Assessment in Treacher Collins Syndrome

Objectives:

The purpose of this investigation was to assess the pharyngeal dimensions and the craniofacial morphology of individuals with Treacher Collins syndrome (TCS) when compared to vertical skeletal class II individuals. It is our hypothesis that the upper airways of individuals with TCS are reduced in view of the skeletal pattern and the maxillomandibular dysmorphologies.

Materials and Methods:

Cone-beam computed tomography scans of 26 individuals had the pharyngeal volume (V) and minimal cross-sectional area (mCSA) evaluated. Study group (TCS) was formed by 13 scans of patients with TCS (7 males and 6 females; 20.2 ± 4.7 years). Control group (CG) assembled 13 scans of nonaffected individuals with the same type of skeletal pattern (2 males and 11 females; 26.6 ± 5.4 years). Cephalometric data of maxillomandibular position, maxillomandibular dimensions, and growth pattern were assessed. Statistical analysis ( P ≤ .05) included Student t test and Pearson correlation coefficient.

Results:

Although reduced, pharyngeal V and mCSA of TCS were not statistically different from the CG. On both groups, mCSA was mostly at the oropharyngeal level. Individuals with TCS presented retrognathic chin, reduced maxillomandibular dimensions, and increased clockwise rotation of the palatal plane. Maxillary and mandibular lengths were correlated with pharyngeal V and mCSA.

Conclusions:

The pharyngeal dimensions of individuals with TCS are impacted by the micrognathia and retrognathia. In association with the skeletal pattern, the reduction of the airways, although not statistically significant, may explain the increased prevalence of airways disorder in this syndrome.

Pharyngeal airway spaces in different skeletal malocclusions: a CBCT 3D assessment

Objective: To three-dimensionally evaluate the upper pharyngeal airway spaces in adults with different anteroposterior and vertical skeletal malocclusions.Methods: In this retrospective study, three-dimensional airway volume and the minimum constricted areas of 120 adults were measured from cone beam computed tomography volume scans. The sample was divided into skeletal Class I and Class II and subdivided into average and long face malocclusions in each skeletal Class. Airway volumes of the naso-, palato-, and glossopharynx, and the minimum constricted area were measured and compared.Results: Skeletal Class II reduced glossopharyngeal airway volume and larger total minimum constricted area in average faces and more nasal minimum constricted area in long faces. Skeletal Class II with long face significantly increased palatopharyngeal and glossopharyngeal airway volumes as well as larger palatopharyngeal minimum constricted area (p < 0.05).Conclusion: This paper found a likely association between jaw skeletal classification and airway dimensions.

Cone-beam evaluation of pharyngeal airway space in adult skeletal Class II patients with different condylar positions

OBJECTIVES

To test the null hypothesis that there is no significant difference in pharyngeal airway space among adult skeletal Class II patients with different condylar positions using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

The CBCT records of 60 patients with skeletal Class II malocclusion (ANB angle ≥ 4°, Wits ≥ 0) were selected from the CBCT database. According to the condyle position, the patients were divided in three groups: anterior group (CD ≤ -12%), centric group (-12% ≤ CD ≤ +12%), and posterior group (CD ≥ +12%). Three-dimensional (3D) pharyngeal airway models were reconstructed using InvivoDental software 5.1.3. The volume and area of the pharyngeal airway space were measured in the 3D airway model.

RESULTS

The volume and area of the pharyngeal airway space in the centric group were significantly smaller than those in the posterior group ( P < .01). The volume and area of the pharyngeal airway space were smallest in the anterior group and significantly increased in the centric and posterior groups ( P < .001).

CONCLUSIONS

The null hypothesis was rejected. Significant differences were noted in pharyngeal airway space among adult skeletal Class II patients with different condylar positions.

A retrospective study: does upper airway morphology differ between non-positional and positional obstructive sleep apnea?

Objective

The objective of this study was to explore the differences in upper airway morphology between positional (POSA) and non-positional (NPOSA) obstructive sleep apnea.

Methods

This retrospective study enrolled 75 patients (45 NPOSA and 30 POSA) who underwent polysomnography (PSG) and computed tomography (CT). The differences in, and relationships of, the PSG values and CT data between POSA and NPOSA were analyzed.

Results

Significant (p < 0.05) differences between the two groups were found in the apnea/hypopnea index (AHI), lateral-AHI (L-AHI), soft palate length (SPL), cross-sectional palatopharyngeal area, and the coronal diameter (CD) of the palatopharyngeal area at the narrowest part of the glossopharynx, which were all higher in POSA, except for SPL, AHI, and L-AHI. L-AHI was correlated with the cross-sectional area (r =  − 0.306, p = 0.008) and CD (r =  − 0.398, p < 0.001) of the palatopharyngeal area, the cross-sectional area (r =  − 0.241, p = 0.038) and CD (r =  − 0.297, p = 0.010) of the narrowest level of the glossopharynx, the CD of the glossopharynx (r = 0.284, p = 0.013), body mass index (BMI, r = 0.273, p = 0.018), SPL (r = 0.284, p = 0.014), and vallecula-tip of tongue (r = 0.250, p = 0.030). The SPL and CD at the narrowest part of the glossopharynx were included in the simplified screening model.

Conclusions

In NPOSA, the CD of the upper airway was smaller, and the soft palate was longer, than in POSA. These differences may play significant roles in explaining the main differences between NPOSA and POSA.

A retrospective cephalometric study on upper airway spaces in different facial types

Background

Craniofacial growth pattern has been correlated with variations in size of the upper airway spaces. The objective of this study was to evaluate the nasopharyngeal, oropharyngeal, and hypopharyngeal airway spaces variations according to the craniofacial growth pattern, by comparing brachyfacial, mesofacial, and dolichofacial in Angle Class I individuals.

Methods

To measure the spaces, 45 lateral teleradiographs were used and divided into 3 groups per the craniofacial growth pattern, determined by the Tweed cephalometry angular measurements: FMA and Y-axis. To evaluate the airways, sleep apnea cephalometry was used, containing 28 points that compose 14 factors. Three groups were compared relative to each of the 14 sleep apnea cephalometry measurements. Adherence test to the normal curve was performed. For the non-normally distributed data—measurement of the inferior pharyngeal space—the Kruskal-Wallis test was used for comparison between the groups. For the remaining data, the distribution was normal and ANOVA test was used.

Results

Statistically significant difference was verified among the groups for the measurement of the median posterior-palatal space, with the difference being pointed out by the post hoc test between the brachyfacial and dolichofacial groups. For the other measurements, there was no statistically significant difference.

Conclusions

It could be concluded that there was difference in the median posterior-palatal space measurement, in the oropharynx region, which was reduced for individuals with a dolichofacial pattern.

A pilot study for segmentation of pharyngeal and sino-nasal airway subregions by automatic contour initialization

PURPOSE

The objective of the present study is to put forward a novel automatic segmentation algorithm to segment pharyngeal and sino-nasal airway subregions on 3D CBCT imaging datasets.

METHODS

A fully automatic segmentation of sino-nasal and pharyngeal airway subregions was implemented in MATLAB programing environment. The novelty of the algorithm is automatic initialization of contours in upper airway subregions. The algorithm is based on boundary definitions of the human anatomy along with shape constraints with an automatic initialization of contours to develop a complete algorithm which has a potential to enhance utility at clinical level. Post-initialization; five segmentation techniques: Chan-Vese level set (CVL), localized Chan-Vese level set (LCVL), Bhattacharya distance level set (BDL), Grow Cut (GC), and Sparse Field method (SFM) were used to test the robustness of automatic initialization.

RESULTS

Precision and F-score were found to be greater than 80% for all the regions with all five segmentation methods. High precision and low recall were observed with BDL and GC techniques indicating an under segmentation. Low precision and high recall values were observed with CVL and SFM methods indicating an over segmentation. A Larger F-score value was observed with SFM method for all the subregions. Minimum F-score value was observed for naso-ethmoidal and sphenoidal air sinus region, whereas a maximum F-score was observed in maxillary air sinuses region. The contour initialization was more accurate for maxillary air sinuses region in comparison with sphenoidal and naso-ethmoid regions.

CONCLUSION

The overall F-score was found to be greater than 80% for all the airway subregions using five segmentation techniques, indicating accurate contour initialization. Robustness of the algorithm needs to be further tested on severely deformed cases and on cases with different races and ethnicity for it to have global acceptance in Katradental radKatraiology workflow.

Anatomical relation between nasal septum deviation and oropharynx volume in different facial patterns evaluated through cone beam computed tomography

INTRODUCTION

The objective of this study was to establish the anatomical relation between nasal septum deviation (NSD) and oropharynx volume in different facial patterns using cone beam computed tomography (CBCT).

METHODS

Ninety CBCT examinations were analyzed. InVivoDental software was used to evaluate cephalometric image reconstructions in terms of facial type, determined from cephalometric measurements indicative of growth direction; the presence of NSD was also evaluated. ITK-SNAP software was employed for delimitation of the oropharynx. Intra-examiner error methods were recorded. The results were subjected to parametric and non-parametric tests using Bioestat 5.0.

RESULTS

A comparison of facial types revealed a significantly lower prevalence of NSD in the dolichofacial group compared with the brachyfacial and mesofacial groups (P = 0.0101 and 0.0149, respectively). In the total sample, there was a very strong positive relation between the presence of NSD and oropharynx space volume (P = 0.0162). The oropharynx volume was larger in all facial patterns in the presence of NSD.

CONCLUSION

The presence of NSD was not associated with facial type, although the oropharynx volume in patients with NSD increased. Therefore, deviation of the septum influences oropharynx volume.

Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

The upper airway is a complex tissue structure that is prone to collapse. Current methods for studying airway obstruction are inadequate in safety, cost, or availability, such as CT or MRI, or only provide localized qualitative information such as flexible endoscopy. Long range optical coherence tomography (OCT) has been used to visualize the human airway in vivo, however the limited imaging range has prevented full delineation of the various shapes and sizes of the lumen. We present a new long range OCT system that integrates high speed imaging with a real-time position tracker to allow for the acquisition of an accurate 3D anatomical structure in vivo. The new system can achieve an imaging range of 30 mm at a frame rate of 200 Hz. The system is capable of generating a rapid and complete visualization and quantification of the airway, which can then be used in computational simulations to determine obstruction sites.

Cephalometric Assessment of Upper Airway Effects on Craniofacial Morphology

To investigate craniofacial growth deformities in children with upper airway obstruction, this controlled study was performed. Cephalometry is used as a screening test for anatomic abnormalities in patients with obstructive sleep apnea syndrome. Therefore, the current work selected this method to investigate the effect of upper airway obstruction on craniofacial morphology.Patients with upper airway obstruction (104) were compared with 71 controls. Patients with upper airway compromise had mandibular hypoplasia, mandibular retrognathism, and higher hard palates in comparison with controls with no history of airway obstruction. The difference was higher in the older age group.Airway obstruction has significant correlation craniofacial morphology. Our findings support the idea of early assessment and thorough management of mouth breathing in children.

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

Objective

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

Methods

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

Results

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

Conclusion

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

A Method for Accurate Reconstructions of the Upper Airway Using Magnetic Resonance Images

Objective

The purpose of this study is to provide an optimized method to reconstruct the structure of the upper airway (UA) based on magnetic resonance imaging (MRI) that can faithfully show the anatomical structure with a smooth surface without artificial modifications.

Methods

MRI was performed on the head and neck of a healthy young male participant in the axial, coronal and sagittal planes to acquire images of the UA. The level set method was used to segment the boundary of the UA. The boundaries in the three scanning planes were registered according to the positions of crossing points and anatomical characteristics using a Matlab program. Finally, the three-dimensional (3D) NURBS (Non-Uniform Rational B-Splines) surface of the UA was constructed using the registered boundaries in all three different planes.

Results

A smooth 3D structure of the UA was constructed, which captured the anatomical features from the three anatomical planes, particularly the location of the anterior wall of the nasopharynx. The volume and area of every cross section of the UA can be calculated from the constructed 3D model of UA.

Conclusions

A complete scheme of reconstruction of the UA was proposed, which can be used to measure and evaluate the 3D upper airway accurately.