Long-term changes in hyoid bone position and craniocervical posture in complete denture wearers.

Changes in hyoid position in relation to changes in mandibular inclination and craniocervical posture were studied by roentgen cephalometrics in a sample of 24 long-term complete denture wearers over a 15-year period. The measurements were made on lateral occlusion films obtained with the subjects in the sitting position and with the head oriented according to its natural balance. The changes in mandibular inclination ranged from -5.5 degrees to 8.6 degrees, with a mean of zero. The cervical column became significantly more forward inclined (mean, 5 degrees), and the craniocervical angulation became on an average 5 degrees larger. Correlation analyses indicated that the hyoid position was influenced by two postural systems: the changes in mandibular inclination and the changes in cervical and craniocervical posture. The vertical changes in hyoid position in relation to the upper face largely followed the patterns of increase or decrease in mandibular inclination, whereas the horizontal changes mainly followed the changes in cervical inclination and craniocervical angulation.