Elevated levels of nitric oxide in synovial fluid from patients with temporomandibular disorders

Objective. The objective of this study was to measure nitric oxide activity in synovial fluid samples taken from patients with temporomandibular disorders. Study design. We investigated six volunteers without symptoms and 56 patients with temporomandibular disorders. Nitric oxide activity was measured in temporomandibular joint synovial fluid with a highly sensitive and specific chemiluminescence detection method. Results. A detectable nitrite concentration was found in only 1 of 10 joints in the control group. Measurable levels (>0.001 mol/l) of nitrites in the synovial fluid were found in 8 (72.7%) of 11 joints with disk derangement with clicking, 24 (85.7%) of 28 joints with disk derangement with locking, and all 26 (100%) joints with osteoarthritis. The mean nitrite concentrations in the temporomandibular joint synovial fluid in the disk derangement with clicking, disk derangement with locking, and osteoarthritis groups were significantly higher than that in the control group (p < 0.05, p < 0.001, p < 0.001, respectively). Conclusions. These data clearly show increased nitric oxide production in certain temporomandibular disorders and suggest that nitric oxide may play a role in the pathogenesis of synovitis and degenerative changes of cartilaginous tissue and bone of the temporomandibular joint.