Relationship of Upper Pharyngeal Airway Volume and Tongue Position in Different Skeletal Patterns: A CBCT Study

This study aimed to assess the relationship of upper pharyngeal airway volume with tongue position in different sagittal and vertical skeletal patterns using cone-beam computed tomography (CBCT).

CBCT images of 225 participants (149 females, 76 males) over 18 years of age were evaluated in three groups with sagittal Class I, II, and III skeletal patterns. Class I and II individuals were subdivided into three vertical subgroups high angle, normal, and low angle. The CBCT scans were evaluated three-dimensionally, and the volume of the lower nasopharynx (LNP), oropharynx (ORP), and velopharynx (VLP) was calculated in addition to the total upper pharyngeal airway volume (TV). The tongue position (according to Graber’s analysis and D1-D5 and D1’-D5’ lines) was determined, and the tongue height (TGH) was measured. Data were analyzed by one-way and two-way ANOVA, Tukey’s test, and Pearson’s and Spearman’s correlation tests (a=0.05).

The volume of the LNP was significantly larger in Class II than in Class III patients (P<0.05). VLP volume (r>0.5, P<0.05) and TV (r>0.5, P<0.05) in Class I high angle participants had a significant correlation with D1.

The present results showed greater LNP volume in Class II than in Class III individuals. In some variables (VLP, ORP, TV, intraoral airway volume) no significant difference was observed between different sagittal and vertical groups. Most of the airway variables (TV, VLP, ORP) had no correlations with some tongue variables (TGH, D1, D3, D4, D4’, D5, intraoral airway volume) in different skeletal patterns.