The case dental program is fairly new so I don't know much about it. As for the six year OMFS/MD option, I don't really understand the motive for going after the MD. Everyone on here has said it's only a status thing, but a dentist I talked to said he believed that the goal of that program was give someone an overall view of human health as it relates to oral health. The lines get fuzzy though (at least from my limited perspective) between OMFS/MD, OMFS proper, and ENT proper. I suppose that there is overlap though.
Personally, I can't imagine going to 4 years of a dental school and then 6 years of OMFS/MD simply to get a few extra letters after my name. If you're interested in letters, get a Ph.D. and go into academics where it matters.