Objective To evaluate the clinical efficacy of intra-articular injection with 2% chitosan as a treatment for irreducible anterior disc displacement of the TMJ.Methods Total 30 patients with irreducible anterior disc displacement were divided into two groups according to quasi-randomizaion. The patients in test group received intra-articular injection with 1 0 ml of 2% chitosan into upper cavities of the suffered joints,in control group with 12 5 mg of prednisolone. The patients were followed up at the 1st day and 14th day after injection and the maximal mouth opening was measured.Results The maximal mouth opening at 14th day was (36 73±4 69) mm in test group, with 11 73 mm increase from baseline; and (28 53±5 81) mm in control group, with 3 86 mm increase, respectively. The increase of maximal mouth opening in test group was significantly higher than that of control group (P
