The Influence of Temporomandibular Joint Disk Displacement on Craniocervial Posture

Method: Subjects consisted of 170 adult female orthodontic patients who consented to bilateral TMJ magnetic resonance imaging (MRI). Subjects were divided into three groups based on bilateral TMJ MRI: bilateral normal disk position (BN), bilateral disk displacement with reduction (DDR), and bilateral disk displacement without reduction (DDNR). Twenty-four variables from lateral cephalograms were analyzed with one-way analysis of variance to investigate differences in cervical posture and the hyoid bone position with respect to TMJ DD status. Pearson correlation coefficients were calculated to analyze the relationships between the craniofacial morphology and cervical posture or the hyoid bone position.

Result: Subjects with TMJ DD were more likely to have to Class II hyperdivergent patterns with extended cervical posture. The most significant differences were found between BN and DDNR. However, the hyoid bone position was not significantly different among the different TMJ DD statuses. Pearson correlation coefficients showed that extended cervical posture was related with sagittal and/or vertical skeletal morphology.

Conclusion: The present study suggests that cervical posture is influenced by TMJ DD, which may be associated with backward positioning and clockwise rotation of the mandible.