How about applying to combined PhD/DDS programs? A bunch of schools have them. Typically, the programs is set up so that after D2 you do research for a few years, after which you return to finish up D3 and D4. You could go into teaching and do faculty practice at the same time. It's a great thing if you're interested in research, and you will most likely get a lot of financial assistance.
Despite what the person above me says, it is NOT a good idea to apply to separate programs, as it shows ambivalence on your part. A PhD program is not be done to improve your grades for dental school; it is a terminal degree and can last anywhere from 5-7 years. If you wanted, you could apply following your PhD but at applying at the same time wouldn't make sense.