[Multivariable analysis of the associations between transversal maxilla size and upper airway volume]

To assess the relationship between the size of the upper jaw and the volume of the upper respiratory tract in adult patients, both in the form of continuous indicators and in the form of categorical variables.

Cone-beam computed tomography images of all patients (n=365) aged 18-60 years who attended one of the dental clinics in Arkhangelsk (Northwest Russia) from October 2019 through November 2020 comprised the study base. Maxilla size and upper airway volume were assessed using Ez3D-I software. Bivariate analysis of categorical variables was performed using Pearson's chi-squared tests. Continuous variables were compared using unpaired Student's t-test. Independent associations between maxilla size and upper airway volume were assessed by multivariable linear regression analysis adjusted for age and gender.

No associations between maxilla size and upper airway volume were observed in bivariate analysis. Adjustment for potential confounders in multivariable analysis has not changed the initial results on no associations between the studied variables with 95% confidence level.

In contrast with the results of many previous studies, our findings suggest no association between transversal maxilla size and upper airway volume. Patients with reduced maxilla size are equally likely to have normal and reduced upper airway volume. Further research on larger samples is needed to corroborate our findings.