No, a majority of applicants and matriculates take the traditional route, which means they apply during their junior year so as to avoid a "gap year" after graduation. That being said, there is no significant advantage for those who already have a bachelors as opposed to those who plan on receiving one before they matriculate. However, both of those groups DO have an advantage over those who don't plan on earning a bachelors at all. You would have to have exceptional stats in order be accepted without a degree, and some dental schools list a bachelors as a requirement.