Relationship between jaw opening force and hyoid bone dynamics in healthy elderly subjects

PURPOSE This study aimed to examine the relationship between jaw opening force and hyoid bone dynamics and resting position in elderly individuals based on gender. SUBJECTS AND METHODS Subjects were 36 healthy elderly individuals aged ≥65 years without dysphagia (16 men and 20 women; mean age 75.5 years, range 65-88 years). Videofluorographic images during the swallowing of 10 mL of 40% (w/v) barium sulfate were obtained and the degrees of anterior, superior, and hypotenuse displacements of the hyoid bone and maximum/resting hyoid position were evaluated. Jaw opening force was measured three times using a jaw opening force sthenometer; the mean of these three measurements was used for analysis. RESULTS In men, there was a positive correlation between jaw opening force and resting hyoid position and negative correlations among all the degrees of anterior, superior, and hypotenuse displacements of the hyoid bone. In women, there was no statistically significant correlation between jaw opening force and any of the measurement items. There was no statistically significant correlation between jaw opening force and maximum hyoid position in either men or women. CONCLUSION Our findings suggest that low jaw opening force leads to low resting hyoid position only in elderly men, and a lower hyoid position in healthy elderly men results in a larger total amount of hyoid displacement during swallowing. Moreover, a maximum hyoid position in healthy individuals of either gender does not differ depending on their jaw opening force.