Abstract: Objective To investigate bilateral temporomandibular joint of patients with unilateral symptoms in cone-beam computed tomography and research the refrence planes that may be different,providing refernce for the diagnosis of temporomandibular disorders and comparative study. Methods 87 cases with unilateral symptoms were examined by CBCT and the following indexes were observed and analyzed,including horizontal angles of the cross-sectional condyle after the reconstruction in the same patient、the joint space、the macroaxis diameter of condyle and vertical angles of condyle, which were commonly used at oblique position parallelled to the long axis of condyle、the gradient of articular tubercle and the joint space,which could be obtained at sagittal and oblique position vertical to the long axis of condyle.The data obtained was analyzed by paired t tests with SPSS13.0 software package.Results It was shown that there were significant difference between the bilateral measured value of joint space when the angle was 120°in parallel plane、60°and 90°in sagittal plane、60°and 120°in vertical plane(P < 0.05).The diffenrence was more significant when the angle was 90°in sagittal plane(P < 0.01), the other ones were no significant difference. Conclusion To patients with TMD, it is more easily to observe differences between the bilateral measured value of joint space in the sagittal or vertical plane,where the increase of the front joint space can be seen and the construction was more significant for the diagnosis of temporomandibular disorders and comparative study.

Key words: bilateral, temporomandibular disorders，TMD , temporomandibular joint, cone-beam computed tomography,CBCT, comparative study