The computed tomography of elderly TMJDS patients treated with and without splint were studied in three dimensions. The results showed that the condyle was in a retruded position in the glenoid fossa in sagittal dimension and the horizontal condylar angle appeared asymmetry in axial dimension. Under the splint treatment, the retruded condyle can be adjusted to the center of the glenoid fossa and the horizontal condylar angle can be balanced, since the splint may correct the vertical dimension and eliminate the occlusal interferences. This study indicates that the horizontal condylar angle can be considered as a significant factor in diagnosis of TMJDS and evaluation of the outcome of treatment.