I was just on -- Queen Mary 2 -- the first of September. I broke a front tooth at lunch! I was told there was no dentist on. Was told the World Cruise on both Queens would carry a dentist. But for right now, my need right now, no. No dentist on board; the medical facility never carries one.
If you are qualified in dentistry, rather than asking on fan sites, I would imagine the corporate offices of Cunard would be a better source for correct information on Cunard's plans for using dentists, when and if.