ABSTRACT
Objective To investigate the clinical value of MRI in treatment choice of anterior disc displacement with reduction. Methods 1.5 T superconducting MR was used to scan bilateral temporomandibular joints in 72 consecutive patients who were diagnosed by MRI as unilateral(66 patients)/bilateral(6 patients) anterior disc displacement with reduction at closed and open mouth. MRI sequences included oblique sagittal T2 weighted image and proton density weighted image, and 78 joints' images were acquired. According to the severity of clinical symptoms, all joints were divided into severe symptom group (45 joints) and mild symptom group (33 joints). Treatment was performed in severe symptom group , while follow up was conducted in mild symptom group. Disk position(angle between posterior margin of the disc and the condyle vertical line), disk morphology(biconcave, biplanar, biconvex, rounded, folded, thick posterior band), and joint effusion (none effusion, mild effusion, moderate effusion, marked effusion) were evaluated by two radiologists. The observer agreement for image evaluation was calculated using Kappa statistics. Group difference in disk position was compared using t-test and Chi-square test was used to compare group difference in disk morphology and joint effusion. Results The Kappa value between two radiologists were 0.816 and 0.832 (P<0.01) on evaluation of disk morphology and joint effusion. Statistical results indicated that the angles between posterior margin of the disc and the condyle vertical line in severe symptom group (54.2 ± 10.9)° were larger than those in mild symptom group (46.4 ± 9.0)° (t=3.37, P<0.05). There was no significant difference in disc deformation incidence between the two groups (χ2=1.18,P=0.277). The common deformation in sever symptom group was thick posterior band (χ2=5.65, P<0.05), and in mild symptom group was biplanar (χ2=5.67, P<0.05). No statistical difference in joint effusion incidence was observed(χ2=1.02,P=0.312). Moderate and marked effusion were more common in sever symptom group than that in mild symptom group (χ2=6.55,P<0.05). Conclusions MRI is a useful tool for making treatment choice in anterior disc displacement with reduction. Treatment should be given when the following occurred on MRI:moderate anterior disc displacement, disc deformation (excepting for biplanar), moderate or marked joint effusion.