Jane, ORN is osteoradionecrosis, bone death caused by lack of blood supply to the bone due to it being in the radiation field. No injury to the bone and there will probably be no ORN. But extract a tooth, for example, and the bone may not have enough blood supply to heal. That is why people facing major bone trauma, like extractions or implants, may undergo hyperbaric oxygen, HBO, therapy because that temporarily revascularizes the bones, allowing them to heal normally and thus avoiding the dreaded ORN. The awful thing about ORN is that once it gets started, it just keeps going, so much bone can be lost. The only fix is to get ahead of it and remove bone yet undamaged, as far as I know. It is not something anyone, patient or docs, want to deal with.

I ask anyone who has better information to please chime in.