Airway Morphometric Changes Following Prefabricated Myofunctional Appliance in Class II Division 1 Patients: A Clinical Evaluation

Prefabricated myofunctional appliances (PMAs) are designed to improve airway function by advancing the mandible, enhancing tongue posture, and reducing airway resistance, thereby facilitating nasal breathing in children with sleep-disordered breathing (SDB). This retrospective study evaluated the effects of PMAs on airway dimensions in children with skeletal Class II division 1 malocclusion. Patients were selected from a departmental database (2017–2019). The treatment group included children with Class II division 1 malocclusion, an incisor overjet of ≥6 mm, cervical vertebral maturation (CVM) stage III or earlier, and documented myofunctional dysfunction (e.g., adenoid hypertrophy, allergic rhinitis, or mouth breathing), with complete pretreatment and one-year follow-up lateral cephalometric radiographs. Patients with prior orthodontic intervention or poor compliance were excluded. A matched observation group consisted of untreated patients undergoing growth monitoring. Airway dimensions of the nasopharynx, oropharynx, and hypopharynx were measured using cephalometric radiographs, along with McNamara Airway Analysis. The total nasal symptom score (TNSS) was used as a self-report measure. A total of 34 patients (mean age 9.4 years) were included in the PMA group and 29 patients (mean age 9.6 years) in the observation group. Compared with controls, the PMA group demonstrated significant increases in nasopharyngeal (p = 0.044) and oropharyngeal (p = 0.039) airway areas, while changes in the hypopharyngeal area were not significant (p = 0.121). McNamara Airway Analysis also showed a significant improvement in upper pharyngeal airway dimensions (p = 0.018). TNSS revealed significant changes following PMA therapy (p < 0.001). These findings indicate that PMA therapy is associated with enlargement of the nasopharyngeal and oropharyngeal airway in children with skeletal Class II division 1 malocclusion, suggesting functional airway adaptation beyond simple mandibular advancement.