In a study, synovial fluid TNF levels have been shown to be significantly higher in individuals with TMJ pain upon mandibular movement than in those without such pain.43 Nordahl et al., reported that the patients with chronic inflammatory connective tissue disease and associated TMJ pain have elevated TNF levels in the synovial fluid compared to those without pain.44 Also, in a clinical study a high pretreatment level of TNF in the TMJ synovial fluid was found to be associated with TMJ pain. The gene discussed is TNF; the disease is Pain.