Preliminary study: Evaluating the reliability of cone-beam computed tomography images for upper airway volume in orthodontics

Objectives: The primary aim of this study was to evaluate the reliability of cone-beam computed tomography (CBCT) in measuring upper airway volume in orthodontics. The secondary aim was to compare the upper airway volumes between laypeople and military personnel (physically fit individuals). Material and Methods: This study included 36 male participants aged 21–29 years who had no upper airway pathology or history of upper airway surgery. CBCT scans had been previously obtained as part of routine dental checkups using a standardized protocol by the same operator. The digital imaging and communications in the medicine files of the subjects were imported into the 3D analysis software SimPlant ® 17 Pro (Materialize Dental, Leuven, Belgium) to facilitate the measurement of upper airway volume. The upper airway volume was divided into three sections and measured on days 0 and 14 by the same operator. The intrarater intra-class correlation coefficient (ICC) and Bland-Altman plot were used to assess reliability. The upper airway volumes of the laypeople and military personnel were compared using Tukey’s pairwise test. Results: The variables demonstrated excellent reliability across all sections of the upper airway; the Superior part of the upper airway has an ICC of 0.993, the middle part of the upper airway has an ICC of 0.995, and the inferior part of the upper airway has an ICC of 0.989. The ICC for the entire upper airway was 0.987. The intrarater plot for superior airway measurement showed that 8 out of 8 measurements (100%) fell within the limits of agreement. Similarly, the intrarater plot for the middle airway measurements indicated that 8 out of 8 measurements (100%) fell within the limits of agreement. For inferior airway measurement, the intrarater plot revealed that 7 out of 8 measurements (87.5%) fell within the limits of agreement. No significant differences were found between the upper airway volumes of the laypeople and military personnel. Conclusion: Preliminary evidence suggests that CBCT using a standardized protocol is reliable for measuring upper airway volume. Separating the upper airway into three different parts also demonstrated high reliability and reproducibility among the raters. The ability to accurately measure the upper airway enhances the evaluation of the effects of orthodontic treatment by comparing the pre-and post-upper airway volume.