You have to go to a recruiter and join the Navy again. Seriously. It's a different process than doing a simple lateral transfer to something like the Supply Corps.
You would need to fill out all the recruiting paperwork again, and you would need to get medical clearance to join the Navy (it's ridiculous, I know). You wouldn't need to go to MEPS because your PCM can do your physical. You would also need your FITREPs and a conditional release from AD. The reason for the release is because if you go HPSP, you would leave the USN and transition to USNR. If you go HSCP, you give up your commission and would be AD E-7 throughout school (this is the route I would suggest for you, hands down).
You would need to be competitive for, or accepted to dental school. I'm not sure if you're doing your 1st or 2nd DIVO tour, but I honestly don't know if you would be able to do all of this on sea duty. Shore duty is more realistic. And there's the DAT too.
You're looking at least 2 years before you would start dental school. It won't be easy, but if you really want it, I hope you get it!
