You bring up a lot of points here, almost too many to address here. But here goes.
The 33% tax rate is an approximation of what you would expect to face. Check out:
http://www.smbiz.com/sbrl001.html#pis05
The 28% Federal tax rate kicks in at $71,950 per year. The 33% Federal tax rate kicks in at incomes in excess of $150,100 per year. When you factor in state taxes (
http://taxes.yahoo.com/statereport.html ), which can be as high as 8% per year in certain states, youre looking at an effective tax rate in excess of 33%. So 33% per year in taxes is a very reasonable approximation. Now, you will have some deductions to reduce your gross income (which will give you your taxable income), but those deductions can only go so far before the AMT will kick in. So bottom line, youll be taxed around 33% per year.
Contrary to your assertion, many of your overhead expenses are in fact dependent upon how much you bill. It is true that your rent doesnt go up when you see more patients, but nearly every other expense will go up. Assistant salaries, Hygienist salaries, lab bills (the more crown preps you do the more lab bills you have), supply costs, employee insurance costs, 401(k) matching expenses, and about 20 other things that neither you nor I have thought of. If you dont believe me, you can check out dentaltown.com, where most GPs will state that the average overhead is 60%. So for a $1000 procedure, your pre-tax income is $400, with $600 going to overhead. After tax, youre looking at less than $300. So it will take you a lot longer to pay off the $1830 than you think. You cant just bill a patient $1,000 and somehow think that youll walk away with $1,000. It doesnt work that way.
Regarding the 8.25%, that is the number that finaid.org filled in for me. You can get a better rate for some of your loans, but when you go above the maximum (which I believe is around $38,000 per year), the rates will be much higher. And as I am sure you are aware, interest rates have been increased 12 times in the past 16 months (
http://www.msnbc.msn.com/id/9884272/). And with Congress just passing a budget bill that will specifically result in higher interest rates for students (
http://abcnews.go.com/Business/story?id=1437044), I dont think 8.25% is unreasonable. If it was, why would finaid.org be using that number?
At the end of the day, the extra $100K is a lot of money
an extra $1830 of pre-tax income per month that one would need to devote to loans (using the numbers I put forth in my original post). It is not something that can be dismissed as a couple of extra procedures per month. Of course, if you have direct, hard data that contradicts what I am saying, I think everyone here would benefit from that. But do include a link so we can see it for ourselves.
This is the reason why every single dentist I ever talked to told me Go to the cheapest school that will accept you. In my 20 years of practice, no one has ever asked me where I went to dental school. And one of those dentists graduated from an Ivy League dental school! The OP would be wise to consider all of this when making his/her decision.