Check out the military forums.
Basically you have a few of options:
1. Apply to dental and the Navy HPSP scholarship. If you get the scholarship you get a 20,000 sign on bonus and they pay for all your tuition and fees for dental school and you make 2060 a month. In return you owe the Navy four years of service as a dentist.
2. Alternative program, cannot remember the name something like HPCP, where the Navy will not pay for dental school but you get paid as an E-5, with all the perks of being on active duty (medical, time in for retirement, etc.). This option might make more sense if you are going to a cheaper state school and or you plan on making the military a career.
3. Go ahead and do dental school then after join the Navy, def some larger bonuses here. But, if you are planning to go into the Navy anyway options 1 and 2 are much more attractive.