Just because your dad left you 300K does not mean you should blow it all on an overpriced education. If someone left you 80K and you needed a car would you buy a new BMW when a used Honda would do the same job for less? The issue here is the higher price tag doesn't even buy you BMW quality, when a cheaper price would buy you a Maserati (cheaper, but higher quality state school like UCLA/UW/UNC etc).
Metaphors aside, you are correct to think that USC is way too expensive. Think about what all you could do by NOT attending that school and blowing 300K. A state school on average costs around 250K with generous living expenses included. So, option one you could pay for all dental school and have 50K left over for a house payment, capital to invest etc. Option two, you could invest 200K of that money smartly and let it grow for 6-10 years. Using the left over 100K pay for years one and two of dental school since they gain the most interest over the course of dental school and have a low payment of around $900 a month to pay. By living within your means for the first few years out of school you could pay off your loan and then look to start your own practice debt free. This is where the sound investment made earlier comes into play. That 200K could have turned into 250K+ over 10 years and this is a nice chunk of change to invest in a practice.
And for those who keep saying that UOP is worth the extra money to "get done a year earlier," this is a ridiculous comment. Everyone acts like you are only allowed to work 25 years and then call it a career, thus by saving a year at UOP you can magically work 26 and make more money. It still costs around 400K to go to school there with living expenses, thus STILL leaving you with a $3,600 monthly payment for 25 years. Congratulations, you will just come to realize one year earlier that 120K salary is eaten up very quickly to 50K take home after taxes and loan repayments. Those with lower loan payments will be able to secure better loans, bigger loans, and do more with a potential dental practice that those who have huge loans. This translates into a much higher earnings potential and less stress/more monetary freedom/lower interest rates etc. for LIFE!
Anyway...good luck in your decision!