Digital infrared thermographic imaging (DITI) in dentistry is helpful for evaluation of inflammatory disease of maxilla and mandible, temporomandibular disorders, vitality loss of tooth, and injury of the sensory nerve. Diagnostic usefulness of the DITI is obscure. In this study, we are to clarify the facial temperature change according to the temporomandibular joint (TMJ) internal derangement (ID) and the amount of synovial fluid collection within the TMJ. The average temperature of 5 areas on the lateral facial imaging was measured; temporal muscle, temporomandibular joint, cheek, masseter muscle, sternocleidomastoid muscle. TMJ ID was categorized as normal disc position, disc displacement with reduction (DDcR), early state of disc displacement without reduction (DDsR) and late state of DDsR on T1-weighted magnetic resonance imaging (MRI). The amount of synovial fluid collection was divided into not-detected, small, moderate, and large amount on T2-weighted MRI. In unilateral TMJ ID, TMJ area of the DDcR (+0.24degrees C) and masseter muscle area of the early state of DDsR (+0.21degrees C) showed significantly elevated surface temperature. In bilateral TMJ ID, the temperature of masseter muscle area with more severe TMJ ID (-0.21degrees C and -0.19degrees C) was significantly low. The different amount of synovial fluid collection did not show significant temperature difference. Structural disharmonies such as TMJ ID might change the circular activities of the TMJ and surrounding muscular systems. The circular activities might show different features according to the states of the TMJ ID.