Is it difficult to go active duty after a dentistry residency? Do I have to discharge out of the Reserves before rejoining active duty?

1. Difficult, but possible
2. No if you stay Army you will not have to discharge or resign your commission, you would transfer out with a conditional release (DD368) to RA. If you’ve completed the amount of time you agreed to drill as a Reservist, get with your S1 ASAP to complete a conditional release packet - this is the most time consuming because it has to be approved by a G1. Concurrently, you will have to work with an AMEDD recruiter to get your active duty packet squared away and sent up - good luck

I Think AR 135-210 Could Get Yoy4 Years AD From A Reserve Component… Or It Used To...

Best thing to do is to apply for a Regular Army Commission through an AMEDD Recruiter. While you could try to go the route of S-1 and HRC, it’s better to simply request a conditional release from the USAR and drop a packet for Active Duty. Once selected, HRC will work with OCAR to push your discharge, reappoint you into the Regular Army and HRC will work with you on an assignment to and active duty post. Call your local AMEDD recruiter and start working the packet.