The inability to open the mouth is called opening restriction, and opening restriction with rattling may be caused by reversible anterior disk displacement, as follows. Because of the anterior displacement of the joint disk, the main clinical manifestation is the opening and closing of the mouth popping, and some patients have intermittent locking knots or joint strangulation during the opening and closing of the mouth, which can cause opening and closing of the mouth obstacles. Due to the anterior displacement of the articular disk, the condyle crosses the posterior edge of the posterior band of the articular disk during the opening movement, and the initial popping of the opening occurs. As the anterior displacement of the disc increases, the initial ringing of the opening may become mid-opening, or even end-opening. There may be other reasons for the restricted opening with rattling, so it is recommended to go to the hospital to have the cause clarified and then to have the appropriate treatment.