I think funding for HBOT very much depends on where you live/what health authority you're under and what consultant you have. I would be very interested in any research about this as it seems to be a postcode lottery. It would be very useful to have a list of consultants who do believe in HBOT. Certainly, everyone I have met so far has had to get pay for their own HBOT at an MS therapy centre.
I haven't got MS, but the MS therapy centres seem to be the only provision of HBOT apart from the private hospitals.
In Wales HBOT can be funded to prevent ORN if extractions/surgery is needed and also to treat ORN if its already started. Actually getting the funding seems to be very difficult though and is dependent on a consultant recommending it - some consultants don't believe in it so will not recommend.
I probably wont have the extractions - one consultant recommended extractions another said there was more risk having the surgery than letting the teeth fall out themselves and having antibiotics if there is infection.
All the best