[The pathogenesis of osteoradionecrosis].

The microradiographic analysis of thick sections of fragments removed from irradiated patients suffering from osteoradionecrosis has made it possible to bring to the fore two types of bone resorption caused by cells: an osteoclastic one not followed by a relevant osteogenesis, and another, pathognomonic of postradic complications, linked with an altered activity of the osteocytes. Those cells, which have been affected, because of a progressive infection, are responsible for an irreversible widening of the osteoplasts, set in the properly vascularized bone regions, in particular in the wall of haversian canals. The coalescence of widened osteoplats causes polycylic cavities which is a typical feature of osteoradionecrosis. A third type of bone postradic damage consists in a massive demineralization, related to the presence of saliva or pus.