It depends on where you live and how many medical or legal problems you have. My recruiter told me he has two 4-year dental hpsp scholarships reserved for him to give out between now and next october. I'm the only one who has talked to him about getting one, so that's looking good for me as long as my application passes. If you're in an area where the scholarships are more in demand, that could be an issue. Again, this is just what my recruiter told me and he is new to this job. I'm his first hpsp applicant.
Also, with the medical and legal stuff, you could be set back a few months trying to get waivers and supporting documents. You wouldn't even believe all of the medical disquailfications that the military has. Check this list:
http://www.military.com/Recruiting/Content/0,13898,rec_step07_DQ_medical,,00.html
It's a long process, and I hope everything works out in the end for both of us!