Objective To compare the efficacy and radiographic changes after arthrocentesis followed or not followed by intra -articular corticosteroid injection in patients with temporomandibular disc displacement without reduction Methods Ninty patients were enrolled in the randomized clinical trial. After receiving arthrocentesis, either 0.5 mL triamcinolone acetonide plus 0.5 mL saline（experimental group，n=46） or 1 mL saline solution as control（control group, n=44） was injected. Patients were assessed by visual analogue scale（VAS） pain scores and Fricton temporomandibular joint（TMJ） index at first visit before treatment, 3-4 weeks and 6 months after treatment respectively. Transpharyngeal and lateral transcranial projections for temporomandibular joints were taken for imaging evaluation. The pain score of patients with pain complaint were recorded everyday for 1 week after treatment. Results Glucocorticoid injection showed more effective pain control over the first week（P
