Effect of occlusal plane control procedure on hyoid bone position and pharyngeal airway of hyperdivergent skeletal Class II patients.

Objective: To evaluate the effect of occlusal plane control on the hyoid bone position and pharyngeal airway of hyperdivergent skeletal Class II patients during orthodontic treatment. Materials and Methods: Cephalograms of 47 hyperdivergent skeletal Class II subjects with occlusal plane control (OPC), and another 50 subjects without occlusal plane control (NOPC) were selected to compare the effects of the occlusal plane control procedure. Lateral cephalograms before treatment (T1), immediately after treatment (T2), and an average of 12 months after treatment (T3) were obtained, and 17 measurements were analyzed in each group and compared between groups. Results: With respect to the T2−T1 changes, the sagittal discrepancies in both groups were alleviated. In the OPC group, both the occlusal and mandibular plane angles decreased, accompanied by anterior and superior movement and counterclockwise rotation of the hyoid bone. The overall changes from T3 to T1 in each group exhibited trends similar to that induced by treatment. As for pharyngeal airway space alterations, no significant difference in OPC group was presented throughout treatment or retention periods. Conclusions: The customized occlusal plane control procedure was effective for hyperdivergent skeletal Class II patients: The occlusal plane rotated counterclockwise, followed by a counterclockwise rotation of the mandibular plane. The hyoid bone moved anteriorly and superiorly, accompanied by its counterclockwise rotation. However, this procedure did not induce significant alteration of the pharyngeal airway space. [ABSTRACT FROM AUTHOR]