Changes in hyoid bone and tongue position in Class I subjects after orthodontic treatment with rapid palatal expander

Objective To evaluate the effects of the rapid palatal expander (RPE) on the hyoid bone and tongue position in skeletal Class I patients, compared to control groups. Methods Eighty-four Class I subjects, aged 6-14, were selected. Among these, 28 patients were treated with RPE, 28 with function-generating bite (FGB) appliance, and 28 were untreated. Lateral cephalograms taken before (T0) and after (T1) treatment were retrieved. Changes in the hyoid bone and tongue position were evaluated, and the area above the tongue was measured. Results No significant difference in the hyoid and tongue posture was observed across the groups. However, there were significant differences for HC3 (distance from H-point to the third cervical vertebrae), H2H (distance from H-point to SN plane), and TT-Eb (tongue length) between T0 and T1 in all groups. Conclusion The results suggest that hyoid bone and tongue position changes were related to growth rather than treatment.