Objective. Temporomandibular joint (TMJ) patients with disc displacement without reduction have a misaligned disc-condyle structural relation. As the condition becomes chronic, painful osteoarthritic changes may occur. For these patients, splint therapy may help to position the condyle to a more structurally compatible and functional position and to decrease the loading force of articular surfaces. The aim of this study was (1) to evaluate osseous reactions and pain relief in patients with disc displacement without reduction after splint therapy and (2) to use single photon emission tomography (SPECT) bone imaging to compare the results with the opposite joint of the patient.