This study aimed to evaluate the long-term outcome of arthrocentesis and stabilizing splints for the treatment of acute closed lock in patients with bruxism. This study included 20 female patients who were divided into two equal groups and who underwent temporomandibular joint (TMJ) arthrocentesis. Patients in the first group wore a full coverage stabilizing splint following arthrocentesis. The second group underwent arthrocentesis only. The scores for preoperative maximal mouth opening (MMO), protrusive movement (PM), contra-lateral (CL) movement (CLM) and visual analogue scale (VAS) scores for pain and dysfunction were compared with the follow-up scores obtained by the questionnaire and clinical examination. Statistical evaluation of the baseline and follow-up data was made with the t-test. The follow-up period was 12 months. There was a significant ( P < 0.001) increase in the MMO, CL and PMs during the longer-term follow-up period for group 1, while there was a significant decrease ( P < 0.019) in these parameters for group 2. The pain and dysfunction levels at follow-up were significantly ( P < 0.001) lower than the preoperative values. Ninety percent of patients in group 2 showed pain and dysfunction scores that increased significantly ( P < 0.001) and ranged from moderate to severe. The overall success rate was 90% for group 1 and 30% for group 2. In conclusion, arthrocentesis and a stabilizing splint are the treatment of choice for acute closed lock of short duration in young patients with bruxism.