You can try banks in your country. I'm from Canada, and the banks here are telling me that if I get accepted at an American or Canadian Dental school they are willing to lend me 150-200k Canadian Dollars.
If I want more (ie. 300-400k), I can get it, but I need a cosigner at that point.
The banks in Canada call this a Line of Credit. It means that the money is there when you need it, but as soon as you take it out they are charging you interest (in Canada they are willing to lend this to us at Prime, which I believe is 3% in this terrible economy). However, you aren't obligated to make any payments until after you graduate school and any residences/specialty training. But the interest will keep accumulating...
To get an American Bank loan, I'm pretty sure you need an American citizen co-signer.