Just like darkknightzzz said, if it's something really impressive on your application, it better have a letter of recommendation with it basically. If you spent tons of hours with a dentist, they want to see that that same dentist wrote a LOR. If you have volunteered a lot somewhere, you should get them to send in a LOR too. I think they are aware that smaller numbers are probably fudged on many applications though, but they are pretty good at determining who's trying to pull a fast one, especially in the interview.
It's best to keep things as accurate as you can.