Osteoradionecrosis of the jaws: current understanding of its pathophysiology and treatment.

During the past 80 years a number of theories about the pathogenesis of osteoradionecrosis (ORN) have been proposed, with consequent implications for its treatment. Until recently tissue hypoxia and its consequences were accepted as the primary cause, and this led to the use of hyperbaric oxygen (HBO) for both treatment and prevention of complications of radiotherapy in the head and neck. The benefit of HBO has not been validated. A new theory for the pathogenesis of ORN has proposed that damage to bone is caused by radiation-induced fibrosis. Cells in bone are damaged as a result of acute inflammation, free radicals, and the chronic activation of fibroblasts by a series of growth factors. New treatments have therefore been devised that include pentoxifylline, a vasodilator that also inhibits fibrosis, and tocopherol (vitamin E) to reduce damage caused by free radicals. Impressive results in terms of reversing the process of ONR have been reported using these agents. It has been suggested that this theory and these agents could be the basis of future treatment and prevention of ORN.