# Association Between Pharyngeal Airway Volume and Craniofacial Morphology in Skeletal Class I and Class II Adult Patients Assessed Using Cone Beam Computed Tomography

## TL;DR

This study found that adults with Class II malocclusion have smaller nasal and total pharyngeal airway volumes compared to those with Class I malocclusion.

## Contribution

The study introduces a CBCT-based analysis of airway volume differences between skeletal Class I and II adults, linking craniofacial morphology to airway dimensions.

## Key findings

- Class II patients had significantly lower nasopharyngeal and total airway volumes than Class I patients.
- BMI was significantly higher in Class I participants compared to Class II participants.
- No significant correlations were found between BMI and airway volume in either group.

## Abstract

Introduction

This study aimed to determine whether pharyngeal airway volumetric differences exist between orthodontic subjects with skeletal Class I and Class II adult participants, and to assess the correlation between age, sex, and body mass index (BMI). The identification of these relationships might enhance orthodontic diagnosis, airway risk assessment, and treatment planning.

Materials and methods

A prospective observational study was conducted on 32 participants (aged 18-28  years) who were equally divided into dentoskeletal Class I (n = 16) and skeletal Class II with dental Class II Division 1 (n = 16) groups, each with a balanced sex distribution. Cone beam computed tomography (CBCT) scans were acquired using the Carestream 9300 Select (Carestream Dental LLC, Atlanta, GA) system with a field of view (FOV) of 10 × 10 cm, 90 kVp, 4  mA, and a voxel size of 180 µm. Pharyngeal airway volumes, such as nasopharyngeal (NPV), oropharyngeal (OPV), and total airway volume (TAV), were delineated using Carestream 3D imaging software (Carestream Dental, Rochester, NY). BMI was calculated from calibrated weight and height measurements. Intra- and inter-examiner reliability was confirmed (intraclass correlation coefficient (ICC) 0.89-0.94). Statistical analysis included the Shapiro-Wilk test, independent t-tests comparing anatomical volumes across malocclusion and sex subgroups, and Pearson correlations (α = 0.05).

Results

The mean age did not differ significantly between sexes or malocclusion types (p > 0.05). BMI was significantly higher in Class  I versus Class  II (25.02 ± 4.17 vs. 21.41 ± 3.62 kg/m²; p = 0.014), with no sex-based BMI differences (p = 0.474). An independent t-test analysis of airway parameters by sex revealed no statistically significant differences between males and females (p > 0.05). No significant correlations were identified between BMI and airway volume (p > 0.05) in either group. Class II patients exhibited statistically significantly lower NPV and TAV (p < 0.05). No significant differences were noticed in OPV between malocclusion groups (p > 0.05).

Conclusion

This study demonstrated that patients with Class II Division 1 malocclusion exhibited significantly reduced NPV and TAV compared to those with Class I malocclusion, highlighting the influence of craniofacial morphology on airway dimensions.