Cephalometric evaluation of pharyngeal airway and tongue space following treatment with Herbst and AdvanSync appliances : A prospective randomized clinical trial.

Objectives: To evaluate and compare pharyngeal airway and tongue space changes after treatment with fixed functional appliances-Herbst and AdvanSync™ (Ormco, Orange, CA, USA) appliances-in skeletal class II patients in pre- and posttreatment lateral cephalograms.

Methods: For this randomized, controlled trial, 40 patients (21 male, 19 female) were divided into two groups-a Herbst group (mean age 12.6 ± 0.67 years) and an AdvanSync group (mean age 12.8 ± 0.66 years). Pre- and posttreatment (appliance therapy duration-8 months) lateral cephalograms were traced using a software program to evaluate pharyngeal airway and tongue space changes.

Results: Nasopharyngeal airway, velopharyngeal airway, glossopharyngeal airway, and hypopharyngeal airway increased in the Herbst group by 2.12 mm (p ≤ 0.001), 2.33 mm (p ≤ 0.001), 2.40 mm (p ≤ 0.01), and 1.57 mm (p ≤ 0.05), while in the AdvanSync group the increases were 1.89 mm (p ≤ 0.001), 1.21 mm (p ≤ 0.001), 1.18 mm (p ≤ 0.001), and 1.53 mm (p ≤ 0.001), respectively. In the Herbst group, tongue length and height increases were 2.04 mm (p ≤ 0.01) and 3.74 mm (p ≤ 0.001), while the values in the AdvanSync group were 2.41 mm (p ≤ 0.05) and 2.69 mm (p ≤ 0.001). The change of the tongue tip from the lower occlusal plane was 0.69 mm (p ≤ 0.001) in the Herbst group and 0.77 mm (p ≤ 0.001) in the AdvanSync group. The velopharyngeal airway dimension was correlated positively with that of the retroglossal oropharyngeal airway, which in-turn positively correlated with the laryngopharyngeal airway which correlated well with the distance of the tongue tip from the lower occlusal plane.

Conclusions: The airway dimensions and tongue parameters increased significantly in both treatment groups in the present study. These changes were higher in the Herbst appliance than in the AdvanSync group, except for the distance of the tongue tip from the lower occlusal plane. A significant difference between the pharyngeal airways was found only for the retropalatal oropharyngeal airway.