Objective This study aims to evaluate the effectiveness of arthrocentesis on Wilkes Ⅲ stage patients. Clinical examinations and magnetic resonance imaging (MRI) findings before treatment and six months after treatment were compared and analyzed. Methods A total of 137 outpatients diagnosed with temporomandibular joint internal derangement (TMJID) associated with Wilkes Ⅲ stage through clinical examination and MRI findings from January 2013 to December 2013 were randomly included. All the patients were successfully treated with arthrocentesis. Moreover, all the patients accepted clinical and MRI examination before arthrocentesis treatment and six months after. Clinical examination included visual analogue scale and opening degree, whereas MRI examination included articular disc morphology and effusion in the upper compartments. Statistical analysis was performed using SPSS 20.0. Results Results showed that the average score of visual analogue scale six months after treatment was significantly lower than that before treatment (PP
