Yes, Penny, totally agree with you. It does seem that many patients are not told about the risk of osteoradionecrosis (ORN). I had 7 weeks of radiotherapy in 2008 (for an unknown primary - so I was blasted both sides of my head & neck). I already had periodontal disease and had lost a couple of teeth to that before the treatment, so I was very high risk for getting ORN - yet I still wasn't warned. Last year I was diagnosed with early stage ORN. I feel quite angry that I wasn't warned (I was given a form with several possible side effects to sign, but ORN was not listed. Although I was told how important it is to keep to a strict dental hygiene routine, I understood it to be because I was more at risk of loosing my teeth through periodontal disease rather than to try to prevent ORN - very different outcomes!
Hyperbaric oxygen therapy may be something for you to look into for your husband. I know many people say that there is insufficient evidence for it, but many do believe in it and use it.