to bres:
That's good advice from Nycdoc. Let me add that having previous exposure to the dental field counts in your favor when you get an interview, because you can tell the interviewer up front that you are familiar with the field and wouoldn't mind being a dentist for the rest of your life!
When I was being interviewed for admission, I had no problems answering the same question everyone dreads: "why do you want to be a dentist?" I tell them I've been exposed to it all my life (dad is a dentist) and so I'm very familiar with the profession and would love to be a part of it. All the interviewers who asked ate it up LOL, especially when I started describing some of the procedures I've seen. The interviewers start thinking, "hey, this guy will fit right in. Let's take him!"
The candidates who usually get weeded out first are the non-committal ones who couldn't satisfactorily answer that question.
Good luck!