The hyoid bone position in adult individuals with open bite and normal occlusion

The position of the hyoid bone was studied in 39 adult subjects with long face syndrome and an open bite of at least 2 mm (16 males and 23 females) and 43 adult subjects with normal Class I occlusion (25 males and 18 females). Several measurements were used to determine the horizontal, vertical, and axial orientation of the hyoid bone. Comparisons were based on paired t-test, which were performed separately for the male and the female groups. Most of the horizontal measurements showed no difference in the position of the hyoid bone in both male and female open bites when related to normals. As far as vertical measurements only the distance from hyoid bone to palatal plane was found significantly greater in the male open bite group due to the position of the palatal plane in the development of this dentoskeletal malocclusion. The hyoid axis formed significantly higher angles with the basion-nasion plane as well as with the palatal plane in the open bite groups, while there was no difference in the angle formed by hyoid axis and mandibular plane. The findings strongly suggest that hyoid bone moves in close conjunction with the pharynx, cervical spine, and mandibular plane in patients with entirely different skeletal patterns.