So, you made a few threads back in 2009 when you were a college freshmen about how difficult it is to become a dentist and then proceeded to coast through 4 years of undergrad with no volunteering, shadowing, etc. and now you want to take another shot at it? You claim that you didn't know what you wanted to do yet there are posts from 4 years ago saying how you wanted to pursue dentistry.
You had an entire undergraduate career to prep along with the wealth of information this site provides, and even if you didn't want to pursue dentistry you could have at least put in enough effort to do well in your classes just in case.
I'm not trying to be a dick but seriously what happened?