You are making an assumption that I don't know is entirely correct. You say that you think your GPA will be lower at UPenn because, I gather, you are thinking that since there is a higher calibre of students at UPenn (based on admissions statistics) that you will be ranked lower in your class at UPenn (ie. more people will be higher than you, and this will lead to you having a lower Dental School GPA if you go to Penn.
1) Straightout of a second year Penn Dental student: they don't curve scores at Penn, so your marks aren't compared to your classmates directly.
2) Penn doesn't rank students after the Top 10.
3) While the top 10 at Penn isn't published, I've heard from penn dental students that you may not even be Top 10, but you can still have a 4.0 GPA.. (the top 10 will be decided based on how many Honours A's you have). How many people at Nova are getting 4.0s?
4. To nail the point home further: it could very well be that the range of Penn GPAs is a 3.7 - 4.0 and the mean is a 3.9, whereas the range of Nova GPAs is a 3.0 - 3.95 and the mean is a 3.5. Thus, even if you are in the middle of your class at Penn, or even lower, you would still be getting a higher GPA than majority of the students at Nova...
See, my point is, grade inflation is a big deal and you should be weary of the assumptions you are making.