Various molecular and inflammatory mediators, and matrix metabolites have been reported in the synovial fluid of patients with temporomandibularjoint disorders. Additionally oxidative stress and the accumulation of free radicals may lead to tissue damage in all tissues, including the temporomandibular joint. These molecular events can trigger the degradation of collagen, hyaluronic acid, and proteoglycans, leading to the development of articular pathology. In this paper, the literature is reveiwed with an emphasis on synovial fluid, and the scientific evidence categorised to theoretically consider the aetiology and pathology of temporomandiblar joint disorders.