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

Upper Airway Dimensions among Different Skeletal Malocclusions: A Retrospective Observational Study by Cephalometric Analysis

The aim of the present work was to investigate the upper airway dimensions in adult non-orthodontic patients, equally divided according to their skeletal class.

METHODS

In this retrospective cross-sectional study, lateral cephalometric radiographs of adult patients referred for orthodontic consultation were collected. Cephalometric tracing was performed with dedicated software. For each measure, descriptive statistics were calculated. Cephalometric measurements between the different skeletal classes were compared. Linear regressions were performed between upper airway diameters and cephalometric measurements, sex and age. Significance was predetermined for p < 0.05.

RESULTS

Lateral cephalometric radiographs of 120 patients were reviewed. Nasopharynx length (NL) and depth (PD) measurements were significantly shorter in skeletal class III patients (p < 0.05). The superior pharyngeal airway space (SPAS) was found to be significantly shorter in class III patients as compared to class II patients (p < 0.05), and the mean airway space (MAS) of class I patients was found to be significantly shorter compared to class II patients (p < 0.05). Palate length (PL) values were found to be significantly longer in class I (p < 0.05). Linear regressions showed that the sella-nasion-A point angle (SNA) and Riedel's angle between point A, the nasion and point B (ANB) significantly influenced NL and PD (p < 0.05).

CONCLUSIONS

Class III patients show significantly shorter nasopharynx measurements; clinicians should consider that this sagittal discrepancy could be related to an altered anatomy of the upper respiratory tract.

Validation of a Finite Element Model for Clinical and Virtual Evaluation of the Changes in Airway Dimensions Following Class III Bimaxillary Orthognathic Surgery

Introduction

The aim of this study was to evaluate pharyngeal airway changes in adult skeletal Class III cases whose bimaxillary surgical treatments were planned with different amounts of maxillary and mandibular movement using lateral cephalometric radiographs and finite element analysis (FEA). Our null hypothesis was that bimaxillary orthognathic surgery in which maxillary forward movement (MF) is greater than mandibular backward movement (MB) will result in more expansion of the pharyngeal airway.

Materials and Methods

A total of 31 individuals (11 females, 20 males) with class III skeletal deformity were included in the study. Patients who underwent bimaxillary orthognathic surgery with greater maxillary advancement (MF > MB) were categorized in Group 1 (n = 15), and those with greater mandibular set-back (MB > MF) as Group 2 (n = 16). Changes in airway dimensions were evaluated from lateral cephalometric radiographs. In addition, FEA modeling was used to determine pharyngeal airway changes with 5 different MF/MB combinations performed in skeletal class III bimaxillary surgeries.

Results

Nasopharyngeal and oropharyngeal airway dimensions increased in direct proportion to the amount of MF. Hypopharyngeal volume decreased compared to preoperative value in direct proportion to the decrease in MB. According to the FEA models, total pharyngeal airway volume decreased when MF was less than or equal to MB, was nearly unchanged when MF was 2 mm greater than MB, and increased when MF was 4 mm greater than MB. The results of FEA and lateral cephalometric analysis were compatible.

Conclusion

Our results supported the null hypothesis. We concluded that when possible, planning slightly more maxillary advancement than mandibular set-back will not have an adverse impact on the airway. Although the skeletal deformity only causes forward displacement of the mandible, dividing the skeletal correction between the maxilla and mandible may be considered to avoid the risk to patients' quality of life in terms of respiratory function.

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.

Evaluation of pharyngeal airway and hyoid bone position in skeletal Class 1 individuals with different vertical growth patterns in Turkish population

Amaç: Bu araştırmada, iskeletsel Sınıf 1 ilişkiye sahip bireylerde dik yön büyüme paterninin farengeal havayolu boyutlarına ve hyoid kemik pozisyonuna etkisinin değerlendirilmesi amaçlanmıştır. Gereç ve Yöntem: Bu retrospektif araştırmaya, ANB açısı temel alınarak iskeletsel Sınıf 1 ilişkiye sahip toplam 72 birey (36 kadın, 36 erkek; ortalama yaş: 17.78 ± 1.39 yıl) dahil edildi. Bireyler dik yön büyüme paternine göre; normodiverjan, hipodiverjan ve hiperdiverjan olmak üzere 3 gruba ayrıldı. Lateral sefalometrik radyografiler üzerinde farengeal havayolu ve hyoid kemik pozisyonu ölçümleri, 1 açısal ve 10 lineer ölçüm kullanılarak yapıldı. Verilerin analizinde bağımsız örneklem t-testi ve tek yönlü varyans analizi (ANOVA) kullanılarak grup içi ve gruplar arası farklılıklar değerlendirildi (p&lt;0.05). Bulgular: Verilerin grup içi karşılaştırmalarında farengeal havayolu boyutlarına ait ölçümlerin cinsiyetler arasında benzer olduğu (p˃0.05) ve tüm gruplarda hyoid kemiğin servikal vertebralara ve mandibular düzleme olan uzaklıklarının kızlarda anlamlı düzeyde daha az olduğu görüldü (p&lt;0.05). Normodiverjan, hipodiverjan ve hiperdiverjan bireylerin farengeal havayolu boyutları ve hyoid kemik pozisyonunda istatistiksel olarak anlamlı farklılıklar olmadığı belirlendi. Sonuç: Normodiverjan, hipodiverjan ve hiperdiverjan bireylerde farengeal havayolu boyutlarının ve hyoid kemik pozisyonlarının benzer olduğu görüldü. Bununla birlikte, tüm gruplarda erkeklerde hyoid kemiğinin kızlara göre daha aşağıda ve daha önde pozisyonlandığı belirlendi.

Assessment of the accuracy of imaging software for 3D rendering of the upper airway, usable in orthodontic and craniofacial clinical settings

BACKGROUND

Several semi-automatic software are available for the three-dimensional reconstruction of the airway from DICOM files. The aim of this study was to evaluate the accuracy of the segmentation of the upper airway testing four free source and one commercially available semi-automatic software. A total of 20 cone-beam computed tomography (CBCT) were selected to perform semi-automatic segmentation of the upper airway. The software tested were Invesalius, ITK-Snap, Dolphin 3D, 3D Slicer and Seg3D. The same upper airway models were manually segmented (Mimics software) and set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the upper airway model obtained with semi-automatic software and the GS model, and to perform the surface-to-surface matching analysis. The accuracy of semi-automatic segmentation was evaluated calculating the volumetric mean differences (mean bias and limits of agreement) and the percentage of matching of the upper airway models compared to the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analyzed for software comparisons.

RESULTS

Statistically significant differences were found in the volumetric dimensions of the upper airway models and in the matching percentage among the tested software (p < 0.001). Invesalius was the most accurate software for 3D rendering of the upper airway (mean bias = 1.54 cm³; matching = 90.05%) followed by ITK-Snap (mean bias =  - 2.52 cm³; matching = 84.44%), Seg 3D (mean bias = 3.21 cm³, matching = 87.36%), 3D Slicer (mean bias =  - 4.77 cm³; matching = 82.08%) and Dolphin 3D (difference mean =  - 6.06 cm³; matching = 78.26%). According to the color-coded map, the dis-matched area was mainly located at the most anterior nasal region of the airway. Volumetric data showed excellent inter-software reliability (GS vs semi-automatic software), with coefficient values ranging from 0.904 to 0.993, confirming proportional equivalence with manual segmentation.

CONCLUSION

Despite the excellent inter-software reliability, different semi-automatic segmentation algorithms could generate different patterns of inaccuracy error (underestimation/overestimation) of the upper airway models. Thus, is unreasonable to expect volumetric agreement among different software packages for the 3D rendering of the upper airway anatomy.

Long-term airway evolution after orthognathic surgery: Systematic Review

Orthognathic surgery is a procedure that consists of correcting the abnormalities of the maxilla, mandible or both. Maxillary movements have a direct effect on the upper airways. For this reason, in the preoperative period, bone movements should be carefully analyzed and planned to avoid causing any damages to the airways. The goal of this study was to discuss the long-term evolution of the airways after orthognathic surgery. In order to do that, a search was performed through the databases PubMed, Virtual Health Library (VHL) and Scopus, using the acronym PICO strategy and a guiding question to conduct the search. Through the keywords and boolean operators "and" and "or" we found 930 articles. After reading the titles, abstracts and application of inclusion and exclusion criteria, we had 21 articles that were studied in their integrity. At the end of the selection, only 8 studies were included in the review. The postoperative evaluations from the selected studies showed that the airways suffered variations, independently of the patient's facial pattern. In addition, the airways tend to return to initial volumes, but none of the included studies obtained a complete return to the initial airways, even 6 years after surgery. Therefore, more studies with controlled methodologies should be conducted in order to have a better understanding of the airways and their changes.

Comparing Pharyngeal Airway Dimensions and Hyoid Bone Position in the Subgroups of Skeletal Class III Malocclusions: A Cephalometric Study

Aim:

To examine pharyngeal airway dimensions and hyoid bone position according to the subgroups of Class III malocclusion.

Materials and Methods:

This retrospective study consisted of patients divided into three subgroups with skeletal Class III malocclusion. The study included a total of 151 individuals (61 females and 90 males). The authors divided individuals with skeletal Class III malocclusion into three subgroups: maxillary retrognathia, mandibular prognathia, and combined. The study’s cephalometric analysis used eight nasopharyngeal, seven oropharyngeal, two hypopharyngeal, nine hyoid, and four area measurements. One-way analysis of variance was used to evaluate patients. Tukey’s post-hoc tests were used for bilateral comparisons of significant parameters. The results were considered statistically significant at a P < .05 significance level.

Results:

The study found no significant differences between the groups’ pharyngeal airway and area measurements ( P > .05). When the authors evaluated hyoid bone position, a statistically significant difference was found between the three groups’ Hy-A (mm), Hy-S (mm), Hy-SN (mm), and Hy-FH (mm) measurements ( P < .05).

Conclusion:

Linear and areal pharyngeal airway dimensions are similar in subgroups of Class III malocclusions, while the hyoid bone is vertically higher in individuals with maxillary retrognathia.

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.

Correlation of soft palate morphology to growth pattern: A retrospective cephalometric study

Aim

The aim of the present study was to evaluate the radiographic length of velum (LV), width of velum (WV), velum angle (AV), depth of pharynx (PD), Need's ratio (NR), inclination angle (AI) in different morphological types of soft palate according to growth patterns in skeletal class I individuals.

Methodology

80 pretreatment lateral cephalograms of patients with skeletal class I malocclusion (ANB 2--4°) were divided on basis of six types of soft palate and further into three subgroups according to growth pattern and evaluation of LV, WV, angle with the palatal plane, and NR was done. Kruskal--Wallis test was used for the comparison between the groups.

Results

Statistically significant difference was verified among all groups for measurement of NR. The highest NR was seen in Crook type of soft palate (mean 0.9). Similarly, the vertical growth pattern in all the six types of soft palate exhibited a higher NR than the average and horizontal growth pattern group; the highest being exhibited by vertical group in type VI (crook shaped). Velopharyngeal insufficiency is directly related to NR.

Conclusion

Vertical growth pattern has the highest susceptibility to velopharyngeal insuffiency and speech and sleep apnea disorders.

Pharyngeal Airway Modifications in Skeletal Class III Patients Undergoing Bimaxillary Advancement Surgery

PURPOSE

The purposes were to study the pharyngeal airway in patients with skeletal Class III malocclusion submitted to surgical orthodontic treatment and to correlate the alterations with bone movements.

MATERIALS AND METHODS

The sample consisted of multislice computed tomography images from 13 patients obtained before and 6 months after maxillomandibular advancement surgery. The following measurements were obtained using Dolphin Imaging software (Dolphin Imaging, Chatsworth, CA): volume and area of the oropharynx, nasopharynx, and total airway, as well as the most constricted area, anteroposterior and lateral dimensions of the narrowest axial cross-sectional area, and airway length. The paired t test was applied at a significance level of 5%.

RESULTS

Sagittal displacement of the maxilla and mandible was correlated with airway alterations using the Pearson correlation test. Alterations in airway measurements were observed in all patients after surgery. We noted a significant increase (P < .05) in total airway area, oropharyngeal area, and anteroposterior dimension of the most constricted area, as well as a significant reduction (P < .05) in airway length. A significant correlation (P < .05) was observed between nasopharyngeal area and maxillary movement and between airway length and mandibular movement (P < .05).

CONCLUSIONS

The results of this study suggest significant alterations in pharyngeal airway measurements when preoperative and postoperative periods of bimaxillary advancement surgery were compared.

Noncontact identification of sleep-disturbed breathing from smartphone-recorded sounds validated by polysomnography

PURPOSE

Diagnosis of obstructive sleep apnea by the gold-standard of polysomnography (PSG), or by home sleep testing (HST), requires numerous physical connections to the patient which may restrict use of these tools for early screening. We hypothesized that normal and disturbed breathing may be detected by a consumer smartphone without physical connections to the patient using novel algorithms to analyze ambient sound.

METHODS

We studied 91 patients undergoing clinically indicated PSG. Phase I: In a derivation cohort (n = 32), we placed an unmodified Samsung Galaxy S5 without external microphone near the bed to record ambient sounds. We analyzed 12,352 discrete breath/non-breath sounds (386/patient), from which we developed algorithms to remove noise, and detect breaths as envelopes of spectral peaks. Phase II: In a distinct validation cohort (n = 59), we tested the ability of acoustic algorithms to detect AHI < 15 vs AHI > 15 on PSG.

RESULTS

Smartphone-recorded sound analyses detected the presence, absence, and types of breath sound. Phase I: In the derivation cohort, spectral analysis identified breaths and apneas with a c-statistic of 0.91, and loud obstruction sounds with c-statistic of 0.95 on receiver operating characteristic analyses, relative to adjudicated events. Phase II: In the validation cohort, automated acoustic analysis provided a c-statistic of 0.87 compared to whole-night PSG.

CONCLUSIONS

Ambient sounds recorded from a smartphone during sleep can identify apnea and abnormal breathing verified on PSG. Future studies should determine if this approach may facilitate early screening of SDB to identify at-risk patients for definitive diagnosis and therapy.

CLINICAL TRIALS

NCT03288376; clinicaltrials.org.