Temporomandibular disorders (TMD) and endodontic pain often present overlapping symptoms, complicating the diagnosis and treatment of patients experiencing orofacial pain. This observational, retrospective cohort study aims to determine the prevalence of endodontically treated teeth on the side of pain complaint in patients with TMD and to explore the association between TMD diagnoses and the presence of endodontically treated teeth. Dental records of patients treated at the TMD and Pain clinic at the Federal University of Uberlândia was reviewed. The study included 85 patients, and demographic data, TMD diagnosis, and the side of referred pain were extracted from the records. Diagnostic imaging exams, including panoramic and periapical radiographs, and cone beam computed tomography (CBCT), were analyzed to count the number of endodontically treated teeth on each side of the mouth. The study population consisted of 88% (n=70) women, with a mean age of 40.5 ± 16.3 years. A significant association was found between the side of TMD pain and the number of endodontically treated teeth, with more treated teeth on the side of pain complaint (median = 1) compared to the pain-free side (median = 0), with p <
.001. When analyzing specific TMD diagnoses, the association was significant in muscle-related and mixed TMD diagnoses but not in joint-related TMD pain. Additionally, a binary analysis confirmed this association, showing that patients were significantly more likely to have at least one endodontically treated tooth on the side of TMD pain compared to the non-pain side (χ