No one can know for sure. But I would venture to guess that someone who managed to get competitive grades and DAT while juggling a job, volunteering, research, clubs, ect would look a whole lot better than someone who did minimal, if any, activities and had stellar/nearly flawless numbers.
Dental school is a whole nother ball game. When I interviewed at UMN they even said they don't want the type of people who only studied. Being well rounded not only makes you a stronger applicant, but also will help make you a better practitioner.
Note: There is a significant difference between competitive and stellar. Competitive would be at or above a schools class profile, while stellar would, naturally, be stellar.