In response to the original question, I too left Army after 7yrs (3enl, 4off) to finish my prerequisites for dental school. Between divisional/corps deployments and my last job as an Aide, there was no way to finish the requirements for dental school.
I saved and took on educational debt to go back to undergrad for 2 full years. I also worked for a year right after I got out and then worked for a year while I applied and waited for dental school to start.
I'm in my 3rd year now and looking back, it was all worth it. The HPSP has taken care of most bills so in the big scheme of things, the education debt is just a drop in the bucket. I just hope that I say it was all worth it 10 years from now!