Correlation of Upper Airway Volume Assessed by Cone-Beam Computed Tomography with Salivary Cortisol and Salivary α-Amylase

Background The Indonesian National Armed Forces have the largest military personnel in Southeast Asia. Physical fitness is important for the overall health of these personnel. Cone-Beam Computed Tomography (CBCT) enables clinicians to accurately evaluate the upper airway volume.Objective This study aimed to investigate the correlation between the upper airway volume and salivary biomarkers, namely cortisol and salivary alpha-amylase (sAA), to introduce novel findings and aid the National Armed Forces in evaluating military personnel during recruitment and annual checkups.Methods This observational study included 30 Indonesian male marines aged 21-29 years. CBCT scans were previously performed using a standardized protocol. Head orientation was analyzed using Frankfort's horizontal, midsagittal, and transporionic planes. Participants were randomly assigned to three exercise intensity groups: Group 1 (intense exercise group) had to run for 12 min and do pull-ups, sit-ups, and push-ups (1 min each); group 2 (moderate exercise group) had to run for 12 min and do pull-ups and sit-ups (1 min each); and group 3 (mild exercise group) had to run for 12 min and do pull-ups (1 min). Saliva samples were collected pre- and post-exercise, with sAA levels analyzed via enzyme-linked immunosorbent assay and cortisol levels analyzed using reversed-phase chromatography.Results The correlation between upper airway volume and cortisol was very weak in groups 1 (r=0.066) and 3 (r=0.168) and moderate in group 2 (r=0.680). The correlation between upper airway volume and sAA was moderate in group 1 (r=0.452), weak in group 2 (r=0.232), and moderately negative in group 3 (r=-0.607).Conclusion There is no clear correlation between upper airway volume and salivary biomarkers, including cortisol or sAA. Upper airway volume is the only factor that determines physical fitness. Overall dynamics, including airway pressure, velocity, aerodynamic forces, and flow resistance, must also be evaluated in future studies.