I suppose I should shed some light to career paths for DDS/PhD.
I have many colleagues that complete the DDS/PhD and are competitive for specialty programs (ortho, perio, pros, etc). Others will go into good post-doc positions to gain more research training. There are many faculty members at my school are DDS/PhD that have active research labs. NIDCR is our major funding agency for dentist-scientists and if you look up NIH reporter, you'll find DDS/PhD professors that are able to compete for these awards. Science is a highly competitive field, but it's possible for dentist-scientists to thrive. For example, my PI has successfully acquired >40million in research funds over the course of his career (Dr. Paul Krebsbach, DDS/PhD scientist, who completed his specialty in Periodontics). Our dean, Dr. Laurie McCauley (DDS/PhD, which training in Periodontics) is also a highly successful dentist-scientist and still runs an active research lab.
I think it's really what you make of it and you have to be in the right environment. Fortunately, at U of Michigan, we pride ourselves in having the best of both worlds. Not many institutions can support dentist-scientists, and they have a significant amount of their work week for research as protected time. Most people that have graduated from our PhD program have secured faculty positions at dental schools at home and abroad. Other faculty will also teach in the clinics, work part-time in private practice, or give continuing education courses in their free time.
Industry is also an option. Although rare, one of our graduates is the (Erika DeBouver) is the Senior Director for Clinical Development of the Rare Diseases Unit at GlaxoSmithKline.
In terms of salary, faculty who have an active research lab and are in senior positions are our school make >200k/year. The ceiling is not as high as private practice of course, but it's not bad. My PI makes 300k/year as the Chair of a department and our dean makes >400k. Not too bad I'd say.
Hopefully this helps.