Purpose: The purpose of this study was to determine the level of tumor necrosis factor-alpha (TNF-alpha) in the temporomandibular joint (TMJ) synovial fluid (SF-TNF-alpha) and blood plasma (P-TNF-alpha) of patients with chronic inflammatory connective tissue disease and investigate its relation to TMJ pain, hyperalgesia, and allodynia.
Patients and methods: Twenty-four patients with a diagnosis of chronic inflammatory connective tissue disease and TMJ pain were included in the study. Visual analog scale, tenderness of the TMJ, and pain at mandibular movements were registered, and the pressure pain threshold and pressure pain tolerance levels were measured. TMJ synovial fluid samples and blood plasma were analyzed for TNF-alpha and the levels related to TMJ pain, hyperalgesia, and allodynia.
Results: TNF-alpha was present in the TMJ synovial fluid of 8 of 24 patients at levels significantly exceeding those in plasma at the same visit. The presence of SF-TNF-alpha showed a significant positive correlation to TMJ pain at maximum voluntary mouth opening and tenderness to posterior palpation of the TMJ.
Conclusion: Local production of TNF-alpha occurs in the TMJ synovium of patients with chronic inflammatory connective tissue disease. Pain on mandibular movement and tenderness on posterior palpation (allodynia) of the TMJ is related to the level of SF-TNF-alpha.