Abstract
The purpose of this study was to clarify the positional relationship between the hyoid bone and the mandible in patients with mandibular protrusion. Pretreatment records, including both CT images and postero-anterior cephalograms, of 15 females were used to generate 11 angular measurements, to study the relationship between the mandible, the hyoid bone and the cervical vertebrae. Using a submental CT view, from CT scan, an imaginary reference line was created perpendicular to the midpoint of a line tangent to the anterior borders of the right and left foramen ovale.
The results were as follows:
1) There was a strong positive correlation between the deviation of ANS-Me in the anteroposterior view and the hyoid bone axis and a strong positive correlation between the hyoid bone axis and the line connecting the most posterior point of both condyles. In addition, there was also a strong positive correlation between the hyoid bone axis and the long axis of the third and fourth cervical vertebrae.
2) There was also a strong positive correlation between the line connecting the most posterior points of both condyles and the long axis of the third and fourth cervical vertebrae.
As a conclusion, the results suggested that the positional relationship of the mandible, the hyoid bone, and cervical vertebrae tended to deviate to the same direction in patients with mandibular protrusion.
