Relationships among nasal resistance, adenoids, tonsils, and tongue posture and maxillofacial form in Class II and Class III children.

•Nasal resistance was significantly greater in Class II than in Class III children.•Nasal resistance in Class II was significantly correlated with inferior tongue posture.•Nasal resistance in Class II was negatively correlated with intermolar width.•Tonsil size in Class III was significantly correlated with forward tongue posture.•Tonsil size in Class III was significantly correlated with mandibular incisor position.•Relationships of upper airway factors differ between Class II and Class III children.