Tongue movements in patients with skeletal Class II malocclusion evaluated with real-time balanced turbo field echo cine magnetic resonance imaging

IntroductionThe aim of this study was to evaluate the deglutitive tongue movements in patients with skeletal Class II malocclusion.MethodsFifty-nine patients (26 male, 33 female) with skeletal Class II relationship were divided into 3 groups according to cephalometric analysis. Group 1 (n = 19) had mandibular retrognathism, group 2 (n = 20) had maxillary prognathism, and group 3 (n = 20) had both mandibular retrognathism and maxillary prognathism. Twenty-two skeletal Class I patients (10 male, 12 female) were also included as the controls.ResultsIn the mandibular retrusion group, the posterior portion of the dorsal tongue moved downward at stage 2 and upward at stage 3; the root of the dorsal tongue was in an inferior and anterior position at stage 2. In patients with both mandibular retrognathism and maxillary prognathism, the middle portion of the dorsal tongue was positioned superiorly at stage 3 relative to stage 1; the tongue tip was retruded at stage 3 relative to stages 1 and 2. In the control group, the middle portion of dorsal tongue was positioned superiorly at stage 3 relative to stages 1 and 2; the posterior portion of the tongue moved upward at stage 2 and downward at stage 3, and tongue-tip retrusion was observed at stage 2 relative to stage 1. Contact of the anterior portion of the tongue with the rugae area of the hard palate decreased in the Class II malocclusion groups relative to the control group. The middle portion of the dorsal tongue was positioned more superiorly in patients with Class II malocclusion during all stages of deglutition. The root of the tongue was more inferior and anterior, and the tongue tip was retruded in patients with Class II malocclusion compared with the control group. The posterior portion of the dorsal tongue was more inferiorly positioned in patients with mandibular retrusion than in the other Class II groups or the controls. In the third stage of deglutition, this portion of the tongue had a superior position in groups 2 and 3 relative to the control group.ConclusionsDentofacial morphology affects the position and movements of the tongue during deglutition, and adaptive changes occur in the tip, dorsum, and root of the tongue. Deglutitive tongue movements in patients with a skeletal Class II relationship are different from those with a skeletal Class I relationship.