In-depth CBCT Analysis of Pharyngeal Airway Dimensions and Hyoid Bone Position in Adults with Skeletal Class II Malocclusions: A Cross-Sectional Study

Abstract Background: Skeletal Class II malocclusion is frequently associated with altered craniofacial morphology, potentially impacting pharyngeal airway dimensions and hyoid bone position. Measuring airway dimensions and hyoid position in skeletal Class II malocclusion is crucial for assessing airway obstruction risk and planning effective treatments to improve breathing and reduce complications associated with obstructive sleep apnea. Aim: This study aims to investigate the dimensions of the pharyngeal airway and the positioning of the hyoid bone in specific subgroups of skeletal Class II malocclusion. Methods: Cone-beam computed tomography images of 124 untreated adult patients (80 females; 44 males) with skeletal Class II malocclusion were retrospectively analyzed. Patients were classified into hypodivergent (Hypo), normodivergent (Normo), and hyperdivergent (Hype) groups based on cephalometric analysis (FMA, AFH, PFH, and gonial angle). Volumetric rendering was performed to assess pharyngeal airway dimensions (width, length, and area) in four cross-sectional planes, using 15 anatomical landmarks and the Frankfort horizontal plane as a reference. Hyoid bone position was also assessed using linear and angular measurements. Statistical analyses included ANOVA and Tukey’s post hoc tests ( P < 0.05). Results: A statistically significant difference was observed in lower pharyngeal plane height, with the Hype group exhibiting reduced dimensions compared to the Hypo and Normo groups. Significant differences were also found in the hyoid position, specifically at the C3Me and C3H levels, indicating a more posterior position in the Hype group. Conclusion: This study demonstrates a significant association between vertical skeletal patterns and both pharyngeal airway dimensions and hyoid bone position in adult Class II malocclusion. The reduced airway space and posterior hyoid position in the Hype group suggest a potential increased risk of upper airway obstruction. These findings emphasize the importance of considering the vertical facial type in the diagnosis and treatment planning of Class II patients, potentially influencing orthodontic and surgical interventions to optimize both dentofacial aesthetics and respiratory function.