MRI study of temporomandibular joint disorder in orthodontic patients

Kim, Tae Woo; Byun, Eun Sun; Baek, Seung Hak; Chang, Young Il; Nahm, Dong Seok; Yang, Won Sik

Abstract

Magnetic resonance imaging(MRI) of the temporomandibular joint(TMJ) is very useful method to diagnose internal derangement of the TMJ because of its high specificity for identification of condyle-disc relationships. The purpose of this study was to evaluate the existence, incidence and severity of internal derangement of th TMJ by the MRI of patients who are suspected to have TMJ disorder. MRI sample was composed of 50 subjects(10 males, 40 females) and the mean age was 22.9 years. 43 subjects of the sample were found to have positive findings. 56% of the subjects with positive findings had ADD(anterior disc displacement) without reduction, and 65% had internal derangement of bilateral joints. Distributions in the types of malocclusion in patients with positive findings, the Angle's classification had shown : the largest 41.9% for Cl II (39.6 for Cl II div 1 and 2.3% for Cl II div 2), 37.2% for Cl III, and 2.3% for the nuidentified. 8.6% of the subjects with positive findings had facial asymmetry and 55.8% had openbite. We can conclude that the percentage of CI II is the highest in patients with internal derangement of the TMJ. Openbite or facial symmetry is considered to be uncompensated or compensated deformity which results from facial skeleton remodeling in the process of degenerative joint disease(DJD) due to TMJ degeneration. Therefore it is recommended to screen the patients with facial asymmetry or openbite by MRI before the beginning of orthodontic treatment. Differential diagnosis is essential because the tendency of relapse is high after the orthodontic treatment and continuous observation of TMJ is needed in patients with TMJ disorder.