The role of oxygen free radicals in idiopathic facial pain.

Patients with chronic facial pain including those with facial arthromyalgia (TMJ dysfunction syndrome) were investigated for evidence of abnormal systemic and intra-articular free radical activity. Chronic facial pain patients showed significantly raised serum 2,3-dihydroxybenzoic acid after an oral dose of 1.2 g of aspirin which indicates increased systemic free radical activity. This was reflected in the TMJ aspirates of the facial arthromyalgia patients which contained thiobarbituric acid-reactive substance (TBA-RS) which is also a product of free radical activity. The synovial aspirates also contained high levels of the hyperalgesic eicosanoid 15-HETE. However, there was no difference between the painful and symptom-free joints, which suggested that in part the clinical features are probably determined by asymmetrical masticatory function or as yet unknown algesic factors such as local cytokine production.