Purpose: This study compared the long-term effects of treatment with a stabilization appliance and treatment with a control appliance in patients with temporomandibular disorders (TMD). Materials and Methods: In a controlled trial, 60 TMD patients with temporomandibular joint (TMJ) pain were evaluated after 10 weeks of treatment with either a stabilization appliance or a control appliance. At the 10-week follow-up, the 60 patients were assigned to one of three groups according to their demand for treatment. Group T, the treatment group, comprised 30 patients treated with a stabilization appliance; group C, the control group, comprised nine patients treated with a control appliance; and group M, the mixed treatment group, comprised 21 patients treated with first a control appliance and then a stabilization appliance. Signs and symptoms were evaluated in all three groups at 6- and 12-month follow-ups. Results: At the 6- and 12-month follow-ups, a significant reduction in TMJ pain as measured on a visual analogue scale was found in all three groups, and a significant decrease in signs and symptoms was found in groups T and M. Conclusion: After 6 and 12 months of use, the stabilization appliance was found to still be effective in the alleviation of signs and symptoms in patients with TMD. Many patients in group C changed to a stabilization appliance at the 10-week follow-up, which significantly reduced the number of patients in this group. Most patients reported positive change in overall subjective symptoms in this trial. The stabilization appliance can therefore be recommended for patients with TMD.