Hello, Flo. HBO, in my case, is used because it causes new capilaries to be formed in radiated bone, which will carry oxygen to the wounds created in the bone by extractions. The treatment following the extractions will, if all goes as planned, heal rapidly because of the high concentration (2.4 regular atmospheres) of oxygen. HBO therapy is also used in wound care to help heal troublesome wounds, such as those suffered by diabetics. It may be that this could be helpful with non-helaing wounds your sister has. I know only about the dental aspect of it, but you might find out more information with a general Internet search, and it would be a good question to ask your sister's doc. And no, I have not yet begun, but I had the checkup today to rule out any contraindications (none) and could begin as soon as next week. I will ask them when I am there and see if they ever treat the condition in which you are specifically interested.
Joanna