Methods: Lateral cephalograms of 82 orthodontic subjects, aged 12-25 years, were pulled from the Orthodontic Clinic at Indiana University School of Dentistry, classified based on the molars relationships into three groups Class I (n= 29), Class II (n= 30), and Class III (n= 23), and manually traced. Following reliability studies, 38 parameters (20 dentoskeletal and 18 airway) were measured and compared among groups using One-way ANOVA. Pearson’s correlation coefficients were used to evaluate the associations of the cephalometric parameters with the airway parameters. The level of statistical significance was set at P < 0.05.
Results: When parameters were adjusted for the different classes of malocclusion (Class I, Class II and Class III), significant statistical differences were detected in multiple cephalometric measurements (ANB, Angle of Convexity, Go-Gn, Co-Gn, total facial height, AFH, LAFH, overbite, and overjet). The differences in the airway parameters were statistically non-significant except for the thickness of the soft tissue of the posterior pharyngeal wall. Significant correlations (r ≥ 0.6) existed between Angle of Convexity and both the thickness of soft tissue of the posterior pharyngeal wall and the vertical dimension of nasopharynx for Class I malocclusions. Mandibular length and the length of the upper bony nasopharynx, overjet and the length of the lower bony nasopharynx were correlated at the same level for Class II malocclusion. The length of the upper bony nasopharynx was correlated with both maxillary and mandibular length. The vertical dimension of nasopharynx was correlated with the LAFH at the same level for Class III malocclusion.
Conclusion: Posterior pharyngeal wall thickness was significantly different among the three classes of malocclusion. Several cephalometric parameters showed significant correlation with the airway measurements.