Pharyngeal Airway Volume in Class II Patients Treated with Herbst and Fixed Mechanotherapy Using Cone Beam Computed Tomography - A Comparative Study from Haryana, India

BACKGROUND Skeletal malocclusions occur because of the defect in the underlying skeletal structure. Mandibular skeletal retrusion is the most common characteristic of class II malocclusion. The purpose of this study was to evaluate pharyngeal airway dimension in Class II patients treated with Herbst appliance and fixed mechanotherapy using cone beam computed tomography (CBCT). METHODS This comparative study was conducted among 30 Class II patients (9 to 15 years of age) selected from the outpatient department of orthopaedics. They were divided into 2 Groups; Group I (15 patients) was treated by Herbst appliance; Group II (15 patients) was treated by fixed mechanotherapy. Pharyngeal airway volume, length and width evaluation were done using CBCT in vivo dental software 5.1 (ANATOMAGE, San Jose, CA). Intergroup comparison was done using independent t tests and level of significance (P < 0.05). Correlation of parameters were carried out using Pearson’s correlation test. RESULTS Significant increase in nasopharyngeal, velopharyngeal, glossopharyngeal, laryngopharyngeal, and total airway volume in Herbst group was observed. Velopharyngeal length, glossopharyngeal length and nasopharyngeal airway width showed significant increase in Herbst group. CONCLUSIONS Treatment of Class II patients with Herbst appliance resulted in increase in pharyngeal airway volume. Herbst therapy induced repositioning of tongue resulting in increased length due to posterior fall of uvula, and hence airway volume increased drastically. KEY WORDS Airway Volume, Herbst Appliance, Class II Malocclusion, Retrognathic Mandible