Clinical Prediction Models for Upper Airway Volume Based on Soft Palate and Airway Lumen Dimensions in Adults With Varying Vertical Skeletal Patterns

Objectives: To determine the intricate associations between soft palate dimensions, pharyngeal airway lumen area, the minimal constricted area of the airway (MinAx), and pharyngeal airway volume in subjects with diverse vertical skeletal patterns, and to develop prediction models that could help clinicians predict upper airway volume using soft palate dimensions, airway lumen dimensions, and MinAx. Materials and Methods: Pre-treatment lateral cephalometric radiographs and magnetic resonance imaging (MRI) scans of 80 women were classified into three vertical skeletal groups based on Frankfort-mandibular plane angle (FMA angle): hypodivergent (FMA < 26.9°, n = 26), normodivergent (26.9°≤ FMA ≤ 34.1°, n = 29), and hyperdivergent (FMA > 34.1°, n = 25). Soft palate dimensions, pharyngeal airway lumen data, MinAx, retropalatal airway volume (RPV), and retroglossal airway volume (RGV) data were measured using MRI. Forward multiple linear regression was used to predict pharyngeal airway volumes. Results: Among the eight predictive models developed, six exhibited strong performance, explaining 50%-77% of the variability in airway volumes. MinAx, RPV, and total pharyngeal airway volume (TPV) were considerably higher in hypodivergent subjects than in hyperdivergent subjects. Hyperdivergent subjects had a longer soft palate length (SPL) than normodivergent and hypodivergent subjects. Conclusions: The present study highlights the necessity of considering soft palate dimensions and airway characteristics in orthodontic treatment planning, especially for patients with varying vertical skeletal patterns. Understanding these relationships can help in predicting potential airway issues and customising treatment plans accordingly.