I had something similar after having two molars removed and the cortex of my mandible thinned during surgery. Had exposed bone for about a year and a half and still have a little around the last tooth on that side of my mouth after 24 months.

The ENT would see little slivers of bone (he called them spicules) either exposed bone from lack of adequate skin cover or sticking through the thin layer of skin covering the mandible. He'd take a big plier looking thing, reach in and snip a piece of mandible and some skin. Said that this was a good way to promote and speed up healing. It took about 18 months of repeating this process until it stopped. He biopsied every little sliver he removed, saying that as a general rule, anything that came out of my mouth was to be biopsied. So another biopsy for your husband could be a very trivial process if it is even needed.

Since it was dead bone, it wasn't going to do any good staying there. It was by biopsying the piece of removed bone that an infection was discoverd and successfully treated with antibiotics.

While your descripton of the white covering could very well be thrush, it is possible that there is more than one thing going on and you should ask your doc on the 12th what his plan is, how often this should be checked, what the possibilities are and what treatment options exist.

You will know more in a few days and it could very well be something that is easily treated.
Best, Sheldon