Magnetic resonance imaging-based joint space measurements in temporomandibular joints with disk displacements and in controls.

OBJECTIVE: Previous studies have discussed a posterior displacement of the condyle as a possible risk factor for the development of disk displacements (DDs) of the temporomandibular joint (TMJ). The objective of this study was to compare the posterior and anterior joint spaces in healthy TMJs with those of patients who present different forms of DDs. STUDY
DESIGN: The anterior and posterior joint spaces from 58 patients with unilateral or bilateral DD with reduction (DDR) or without reduction (DDNR) and from 30 healthy volunteers were measured with 3 sagittal magnetic resonance images (MRIs) from each TMJ in the maximum intercuspid position.
RESULTS: Measurements of anterior and posterior joint spaces showed a good interexaminer reproducibility (rank correlation coefficients ranging from 0.88 to 0.95). Patients with bilateral DDR demonstrated a significantly more posterior position of the condyle, as compared with controls and patients with bilateral DDNR. DDNR presented a significant reduction of the anterior and the posterior joint spaces, leading to a mean concentric position of the condyle. Patients with unilateral DDR or DDNR demonstrated a greater variability of anterior and posterior joint spaces, compared with patients with a bilaterally identical type of DD.
CONCLUSIONS: The data of this MRI-based clinical study indicate that different stages of disk displacements are associated with significant changes of condylar position. The variation of anterior and posterior joint spaces was influenced by the diagnosis of the contralateral joint.