Here's some real life info for you. Those numbers for 4 years that you mentioned, first off, the amount after interest accrues will be closer to an addditional 50% added onto that! So that $2000 suddenly becomes almost $3000 a month. What that then translates into is that inorder to pay your monthly loans, and pay the government(taxes), the first roughly $4000 that you make each month is spoken for. Thats roughly $48000 a year before you get to think about mortgages, car payments, living expenses, etc, etc, etc. Yes, it sounds daunting, but its definately manageable. What alot of folks will do after dental school is consolidate all their loans and spread the repayment period out over a longer period of time. This will reduce monthly payment. Also, most folks will have their loans repayed before the duration of the loan, because its amazing what a little extra each month towards the principle will do to reduced the amount of interest that accrues and hence needs to be repayed.
Here's my situation for example. When I graduated from UCONN almost 5 years ago now(I just seems like yesterday!) I had just over 65000 in loans, I then deferred for 2 years during my GPR, and my monthly repayment is just under $900 for 120 months. I've been adding an extra $200 to $300 per month which goes directly towards the principle(whereas when you start repaying, most of the monthly repayment amount goes towards the accrured interest). By doing this, I'll have the entire amount repayed about 4 years ahead of schedule.
Really think about the private/state school situation. Both types can give you all the clinical skills/education/stepping stones towards a specialty(if thats your thing) that you need, but the state schools will ultimately allow you to keep more of what you make which can be used for other things.