Effects of fixed appliances in correcting Angle Class II on the depth of the posterior airway space: FMA vs. Herbst appliance--a retrospective cephalometric study.

Objective: The objective of this retrospective study based on the metric evaluation of lateral cephalograms was to investigate the extent to which treatment with two different fixed appliances for the correction of Angle Class II influenced the morphology of the extrathoracic airway space (the posterior airway space, PAS).

Patients And Methods: A total of 43 patients with Angle Class II malocclusion were classified into two groups according to the appliance used for treatment: the functional mandibular advancer (FMA; n = 18) or the Herbst appliance (n = 25). Lateral cephalograms were taken of each patient at the start of functional jaw orthopedic treatment (time point T1) and at its completion (time point T2).