A developmental approach to reassessing the constancy of hyoid bone position

The hyoid bone plays a key role in several physiological functions by interacting with the attached muscles. Understanding its kinematics and positional stability is essential for evaluating its functions: swallowing, mastication, intraoral transport, vocalization, and respiration. This study aimed to assess the position of the hyoid bone relative to the cranial base and mandible using cephalometric imaging and to examine its stability.

Cephalometric images of 140 patients were analyzed using specialized software. The positional relationship between the cranial base and hyoid bone was assessed by measuring the Porion-Hyoid distance (Po-Hy) and the angle between the Po-Hy and the Nasion-Porion line (∠CB-Hy). The relationship between the mandible and the hyoid bone and the cervical angle was also evaluated.

The ∠CB-Hy showed a narrow distribution (mean ± SD: 89.2 ± 5.12°). A weak, but statistically significant, correlation was observed between age and the ∠CB-Hy. Additionally, a significant negative correlation was found between the number of missing molars and ∠CB-Hy, while a strong positive correlation was identified between the cervical angle and ∠CB-Hy. The relationship between the cervical angle and ∠CB-Hy was represented by the following linear regression equation: ∠CB-Hy = 0.484 × Cervical angle + 37.4.

Our findings suggest that the hyoid bone maintains a relatively stable position with respect to the cranial base with only slight variation. However, a significant relationship exists between ∠CB-Hy and cervical inclination. Clinicians and researchers should consider this relationship when assessing the hyoid position in clinical and research settings.