The aim of this study was to evaluate the use of splint treatment for therapy of osteoarthritis of temporomandibular joint, and to compare the level of anxiety (State-Trait Anxiety Inventory, STAI) and clinical characteristics between 16 patients and 20 asymptomatic dental school students. Magnetic resonance imaging (MRI) was used for all subjects. Dental students showed a statistically significant higher capacity of mouth opening (p < 0.05), and lower level of anxiety (p < 0.05 for STAI 1, and p < 0.001 for STAI 2) than patients. Patients who had suffered chronic pain before splint treatment had a higher value of anxiety by STAI 1 test (p < 0.05).