CBCT analysis of pharyngeal airway volume and comparison of airway volume among patients with skeletal Class I, Class II, and Class III malocclusion: A retrospective study

Three-dimensional assessment of the nasopharyngeal airway in Down syndrome during the mixed dentition period: a case-control study

OBJECTIVE

In this retrospective case-control study, we aimed to evaluate the nasopharyngeal airway volume of children with Down syndrome (DS) and compare the results with those of control participants well matched for sex and age.

MATERIALS AND METHODS

Fifteen children with DS (mean age = 9.43 ± 0.38 years; 8 boys, 7 girls) and 15 control participants (mean age = 9.51 ± 0.40 years; 8 boys, 7 girls) were enrolled. The nasopharyngeal airway volume and the cross-sectional morphology were measured with cone-beam computed tomography taken for orthodontic treatment. All measurements were assessed by analysis of covariance (ANCOVA) using Bonferroni post hoc pairwise comparison tests. Covariates were body height and body weight, and the ANB angle and the mandibular plane angle. Significance was set at P < .0019.

RESULTS

Nasal airway, superior airway, and total airway volumes of DS participants were significantly smaller than those of the control participants in ANCOVA results adjusted for ANB angle and mandibular plane angle (P = .000). In ANCOVA results adjusted for body height and body weight, no statistically significant differences in the volume measurements were found.

CONCLUSION

The results indicate that the nasopharyngeal airway volume differs between children with and without DS and that the airway volume tends to be smaller in DS children than in children without DS.

Impact of Maxillomandibular Sagittal Variations on Upper Airway Dimensions: A Retrospective Cross-sectional CBCT Evaluation

AIM

This study aimed to analyze the upper airway dimensions in adult patients with different anteroposterior (sagittal) skeletal malocclusions (class I, II, and III) using cone beam computed tomography (CBCT) imaging.

MATERIALS AND METHODS

This retrospective cross-sectional study involved 90 CBCT records from adult subjects who were categorized into three skeletal groups based on their ANB values: Class I (n = 30), class II (n = 30), and class III (n = 30) and were evaluated. The following upper airway measurements were considered: oropharyngeal airway volume, hypopharyngeal airway volume, pharyngeal airway volume, oropharyngeal airway length, hypopharyngeal airway length, pharyngeal airway length, the most constricted site of the pharyngeal airway, and the most constricted cross-sectional area (MIN-CSA) of the pharyngeal airway. Additionally, the volume of the intraoral airway was determined. Pearson's correlation test was employed to evaluate the relationship between age and upper airway dimensions.

RESULTS

Significant differences in upper airway volume were found among skeletal groups in the hypopharyngeal (p = 0.034) and pharyngeal (p = 0.004) regions, with class III patients showing larger volumes compared to class II. Oropharyngeal (p = 0.044) and pharyngeal (p = 0.011) lengths were shorter in class III than in class I. In contrast, the narrowest cross-sectional area of the pharyngeal airway was larger in class III compared to class II (p = 0.003) and class I (p = 0.032). Class III patients had a significantly greater intraoral space volume than class II patients (p = 0.036).

CONCLUSIONS

The present study found significant differences in upper airway dimensions among adults with varying maxillomandibular sagittal relationships. Class III patients had larger hypopharyngeal and pharyngeal volumes, but shorter oropharyngeal and pharyngeal lengths compared to other classes. The narrowest pharyngeal area was larger in class III, with gender and age also influencing airway dimensions.

CLINICAL SIGNIFICANCE

These findings underscore the need to consider skeletal relationships, gender, and age in airway assessments. Accordingly, these factors can help clinicians better understand the correlation between airway dimensions and jaw position for accurate diagnosis and treatment planning of orthodontic and surgical interventions. How to cite this article: Aldhorae K, Ishaq R, Alhaidary S, et al. Impact of Maxillomandibular Sagittal Variations on Upper Airway Dimensions: A Retrospective Cross-sectional CBCT Evaluation. J Contemp Dent Pract 2024;25(10):955-962.

Three-Dimensional Assessment of Upper Airway Volume and Morphology in Patients with Different Sagittal Skeletal Patterns

BACKGROUND

The relationship between respiratory function and craniofacial morphology has garnered significant attention due to its implications for upper airway and stomatognathic development. Nasal breathing plays a key role in craniofacial growth and dental positioning. This study investigated upper airway morphology and volume differences among individuals with class I, II, and III skeletal anomalies.

METHODS

Ninety orthodontic patients' CBCT scans were analyzed to assess the oropharynx and hypopharynx volumes. Skeletal diagnosis was established based on the cephalometric analysis.

RESULTS

A significant volume change in the oropharynx and pharynx was demonstrated when comparing class II with class III anomalies (p = 0.0414, p = 0.0313). The total volume of the pharynx was increased in class III anomalies. The area of the narrowest part of the pharynx (MIN-CSA) significantly decreased in classes I and II compared to class III (p = 0.0289, p = 0.0003). Patients with Angle class III anomalies exhibited higher values in the narrowest pharyngeal segment. Gender differences were significant in pharyngeal volumes and morphologies across malocclusion classes.

CONCLUSIONS

The narrowest segment of the pharynx had the highest values in patients with Angle class III. The volume of the oropharynx was found to be greater in patients with Angle class III versus patients with Angle class II.

Functional therapy and adenotonsillectomy clinical trial for class II malocclusion (FACT-II): protocol for a randomised controlled trial

INTRODUCTION

Class II malocclusion with mandibular retrognathia is a common complication of paediatric obstructive sleep apnoea (OSA), often accompanied by transverse maxillary deficiency. In early orthodontic treatment, a twin block (TB) is a regular functional appliance for correcting this malocclusion. For paediatric OSA, the most common risk factor is adenotonsillar hypertrophy (AHT). Untreated AHT may lead to the persistence and worsening of obstructive sleep-disordered breathing traits, including habitual mouth breathing. Additionally, the clockwise mandibular rotation associated with AHT-induced pharyngeal crowding can undermine the effectiveness and stability of TB treatment. Adenotonsillectomy (T&A) is currently the first-line treatment for paediatric OSA. This proposed trial will investigate the impact of T&A surgery timing on the efficacy and stability of TB functional treatment in children with class II mandibular retrognathia and ATH.

METHODS AND ANALYSIS

This will be a single-centre, parallel-group, superiority randomised controlled trial with participants randomised to intervention (T&A followed by TB treatment) or control arms (TB treatment followed by T&A) in a 1:1 ratio. A total of 40 patients aged 8-14 years, diagnosed with class II mandibular retrognathia and co-existing ATH-induced OSA, and indicated for both T&A surgery and TB treatment, will be recruited at the School and Hospital of Stomatology, Wuhan University. The primary outcomes will be the changes in the apnoea-hypopnoea index and the point A-nasion-point B angle from baseline to postorthodontic treatment between the two groups. Secondary outcomes will include other dental, skeletal, upper airway and soft tissue changes, as well as subjective sleep-related and oral-related quality of life. Outcome changes within each group and between groups will be analysed.

ETHICS AND DISSEMINATION

This study is approved by the Ethics Committee of the School and Hospital of Stomatology, Wuhan University (no. 2022-D07). The research findings will be faithfully disseminated through scientific conferences or published articles.

TRIAL REGISTRATION NUMBER

ChiCTR2200061703 (https://www.chictr.org.cn).

Differences in the effects of orthodontic treatment on airway-craniocervical functional environment in adult and adolescent patients with skeletal class II high-angle: a retrospective pilot study

INTRODUCTION

This retrospective cohort study aimed to compare the change in upper airway and craniocervical posture after orthodontic treatment between adolescent and adult patients with Class II high-angle malocclusion.

METHODS

A total of 12 adolescent (mean ± standard deviation age = 13.0 ± 2.0 years) and 12 adult patients with Class II high-angle malocclusion (mean ± standard deviation age = 23.7 ± 6.4 years) were selected in this study. The lateral cephalograms and cone beam computed tomography images of adolescent and adult patients were taken before and after treatment, which can be employed to evaluate the variables of craniofacial morphology, upper airway, and craniocervical posture through paired t tests, respectively. An independent sample t test was performed to observe the differences between two groups after orthodontic intervention. For adults and adolescents, the correlation between craniofacial morphology, upper airway, and craniocervical posture was determined through Pearson correlation analysis.

RESULTS

In all subjects, the improvements in vertical and sagittal facial morphology after treatment were observed. Anterior and inferior movements of the hyoid bone, an increase of upper airway dimension, posterior tipping of the head and a reduction of cervical inclination in the lower and middle segments post-treatment were identified in adolescence (P < 0.05). Adults displayed anterior movements of the hyoid bone, whereas no significant difference was observed in upper airway dimension and craniocervical posture (P < 0.05). Notable differences were identified in the change of hyoid position and airway volume between two groups (P > 0.05). Mandibular plane inclination, growth pattern, occlusal plane inclination, and chin position were all significantly correlated with craniocervical posture in adolescent patients. Besides, the mandibular growth pattern and chin position in adult patients were significantly correlated with craniocervical posture (P < 0.05).

CONCLUSIONS

Orthodontic treatment is capable of enhancing the facial profile of patients with skeletal class II high-angle while improving their upper airway morphology and craniocervical posture, where adolescents and adults differ substantially in that the former exhibit a more favorable alteration in the airway-craniocervical functional environment.

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.

Three-dimensional evaluation of hyoid bone position in nasal and mouth breathing subjects with skeletal Class I, and Class II

BACKGROUND

This retrospective study investigated the effect of breathing pattern, skeletal class (Class I, Class II), and age on the hyoid bone position (HBP) in normodivergent subjects.

METHODS

A total of 126 subjects (61 males, 65 females) aged 7-9 years and 10-12 years were scanned using cone-beam computed tomography (CBCT). All participants were classified according to the anteroposterior skeletal pattern into (Class I, Class II). Each skeletal group was further divided according to the breathing mode into mouth breathers (MB) and nasal breathers (NB). The HBP was measured accordingly. Independent sample t-test and Mann Whitney U test were used to detect significant differences between the groups, and binary logistic regression was used to identify MB predictive indicators.

RESULTS

The breathing mode and skeletal class affected the vertical HBP in subjects with 7-9 years, while they affected the anteroposterior HBP in subjects with 10-12 years. Regarding the age effect, hyoid bone was located more anteriorly in the older NB subjects, and hyoid bone was more inferiorly in the older age group. A regression equation of the significant variables was formulated, C3-Me (P: 001, OR: 2.27), and H-EB (P: 0.046, OR: 1.16) were positively correlated with occurrence of MB.

CONCLUSION

There were significantly different HBPs among subjects with different anteroposterior skeletal classes, breathing modes, and age cohorts. Moreover, C3-Me, and H-EB were significant predictors and correlated with increased likelihood of being MB subject.

A 3D CBCT Analysis of Airway and Cephalometric Values in Patients Diagnosed with Juvenile Idiopathic Arthritis Compared to a Control Group

Introduction: The temporomandibular joint (TMJ) is affected in 30–45% of juvenile idiopathic arthritis (JIA) patients, with all JIA subtypes at risk for TMJ involvement. JIA patients with TMJ involvement may present with altered craniofacial morphology, including micrognathia, mandibular retrognathia, a hyperdivergent mandibular plane angle, and skeletal anterior open bite. These features are also commonly present and associated with non-JIA pediatric patients with obstructive sleep apnea (OSA). Materials and Methods: The study was comprised of a group of 32 JIA patients and a group of 32 healthy control subjects. CBCT images were taken for all patients and were imported into Dolphin Imaging software. The Dolphin Imaging was used to measure the upper airway volumes and the most constricted cross-sectional areas of each patient. Cephalometric images were rendered from the CBCT data for each patient, and the following cephalometric values were identified: SNA angle, SNB angle, ANB angle, anterior facial height (AFH), posterior facial height (PFH), mandibular plane angle (SN-MP), FMA (FH-MP), overjet (OJ), and overbite (OB). Airway volumes, the most constricted cross-sectional area values, and cephalometric values were compared between the JIA and control groups. Results: For airway values, statistically significant differences were seen in the nasopharynx airway volume (p = 0.004), total upper airway volume (p = 0.013), and the most constricted cross-sectional area (p = 0.026). The oropharynx airway volume was not statistically significant (p = 0.051). For cephalometric values, only the posterior facial height showed a statistically significant difference (p = 0.024). Conclusions: There was a significant difference in airway dimensions in the JIA patients as compared to the control patients. In addition, the posterior facial dimensions seem to be affected in JIA patients. The ODDs ratio analysis further corroborated the findings that were significant.

Volumetric Evaluation of Pharyngeal Airway after Functional Therapy

The aim of this study was to evaluate three-dimensional (3D) effects of Twin-block functional appliance (TB) on the pharyngeal airway by using cone beam computed tomography (CBCT). A total of 30 patients (14 females, 16 males; mean age 12.50 ± 1.23 and 12.83 ± 1.17 years, respectively) with skeletal Class II malocclusion were included in this study and were treated with TB. On the pretreatment (T1) and posttreatment (T2) CBCT scans, volumetric changes in the pharyngeal airway; SNA, SNB, and ANB angles; and bilateral effective mandibular (Co-Gn) and midfacial length (Co-A) were also evaluated. The statistical differences were accessed by Wilcoxon signed-rank tests, and Mann-Whitney U tests were used to analyze the scores of male and female subjects. In this study, an increase was observed in SNB and Co-Gn (p < 0.01) while a decrease in ANB and SNA (p < 0.01 and p < 0.05, respectively) was found. However, increase in midfacial length was not statistically significant (p > 0.05). In the evaluation of volumetric pharyngeal airway changes, statistically significant increases (p < 0.01) in the upper and lower division and total airway volume were determined. Gender differences were insignificant for all measurements (p > 0.05). Volumetric changes in the pharyngeal airway after functional therapy can be successfully evaluated by CBCT images. The anterior repositioning of the mandible by TB increases the mandibular length and pharyngeal airway volume in patients with retrognathic mandible.

A Modified Cosmetic Genioplasty Can Affect Airway Space Positively in Skeletal Class II Patients: Studying Alterations of Hyoid Bone Position and Posterior Airway Space

BACKGROUND

Improving the posterior airway space is one of the most important functions of genioplasty. Studies have shown that the posterior airway space (PAS) can play an important role in the evaluation of obstructive sleep apnea syndrome (OSAS). The purpose of this study is to evaluate the airway safety of our modified technology by observing the impact on PAS in skeletal Class II patients without OSAS.

METHODS

We have modified a cosmetic genioplasty, which can guarantee the continuity of the lower edge of the bilateral mandible by rotating the chin segment clockwise. Fourteen patients submitted to our modified cosmetic genioplasty alone were included in the study. The facial convexity angle and the ratio of the face were measured by analyzing photographs. The position of the hyoid bone and the width of the PAS were measured by analyzing lateral cephalograms. The volume and the cross-sectional area (CSA) of the PAS were measured using 3D reconstruction. The Wilcoxon signed-rank test and paired samples t test were used to assess the significance of differences of the data (p < 0.05).

RESULTS

Soft tissue measurements were statistically different (p = 0.001) and achieved satisfactory results. The position of the hyoid bone moved up (L_X: p = 0.004; L_ML: p = 0.056) and forward (L_Y: p = 0.001; L_CV3: p = 0.016). The increase in the CSA had statistical significance (p < 0.005). There were significant statistical differences in the total airway volume and hypopharynx (p = 0.001), except in the oropharynx (p = 0.096).

CONCLUSIONS

Our modified genioplasty not only achieved better cosmetic results by ensuring the continuity of the lower edge of the bilateral mandible but also exerted a significant positive impact on the posterior airway space for patients with skeletal class II, thus helping reduce the prevalence of OSAS. We hence suggest performing this modified cosmetic genioplasty on the skeletal class II patients with/without OSAS if necessary.

LEVEL OF EVIDENCE IV

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