Dental Access loan is one of the better ones, and is pretty popular among dental students. There are other good ones and they all have their benefits and cons. Your financial aid office will tell you all the details with all the approved/recommended private loans should you need to take them out. Also, your school should offer some kind of loans themselves.
There are plenty of financial sources out there. But, don't sweat it, your financial aid package will explain it all.
it seems like that's a lot of money to owe back now, but consider it this way, once you get out of school and begin to practice, your salary will overwhelm the costs you owe back. Live in an apartment for a few years and work your way up from there Things tend to be bad before they get good (with exception to a few cases).
but, i would look into what Brocnizer2007 said. Sounds like a bullet-proof plan