Work by an oral surgeon on jaw or mouth bones will almost certainly be covered by Medicare Part B, whether the oral surgeon is a physician (M.D.) or not. On the other hand, work done solely on the teeth will not.
Medicare considers most work by non-physician oral surgeons as "dental" rather than "medical," and doesn't cover it. But Medicare Part B can cover treatment that involves a problem with bones of the mouth and jaw if it's the kind of treatment that physicians (M.D.s) also perform. This kind of care would be considered "medical" and so would be covered by Medicare Part B even if performed by a non-M.D. oral surgeon.
For Medicare to cover the treatment, the oral surgeon who provides the care must participate in Medicare, and not all oral surgeons do. So, a patient needs to make sure the oral surgeon's office participates in Medicare. Also, it's a good idea to have the oral surgeon's office request in advance that Medicare cover the procedure. Once the doctor's office receives prior approval for Medicare coverage of the oral surgery, the patient can rest assured that the care will be covered.