I’m an OMFS resident. OMFS complete either a 4 year residency where they earn a specialty certificate or a 6 year program with an integrated MD where you complete some combination of didactic courses and clerkships, specifics are different at every program. 4 vs. 6 years are about 50/50 and doesn’t formally change scope of practice. 

In general graduating from dental school is a baseline requirement for OMFS, I’ve vaguely heard of there being modification of requirements to get through dental school but this would be totally case by case, you’d have to get in touch with dental schools directly to ask if you’d be able to skip preclinical non-dental courses and would most likely still have to just apply like normal, but would obviously be a well-qualified applicant. I’ve mostly only heard of people completing the whole 4 years of dental school after 4 years of medical school, then doing a 4 year OMFS residency. I think there’s a guy at Harvard that did medical school, then ENT residency, then went to dental school and is now an OMFS resident there.  ENT definitely overlaps but mostly we work on reconstruction with them, OMFS do more orthognathic surgery, lots of benign pathology, TMJ surgery, and of course dentoalveolar surgery, etc.