Take it from a senior in dental school at a ranked school who had his grades suffer significantly while studying for the NBME CBSE in a system where no time off was given. Grades suck and clinical stuff is some of the most subjective crap you've ever seen in your life. Do yourself a favor, go to a school with strong science curriculum, P/F (eg. Columbia, UCSF, UCLA, Harvard, UPenn ect), rock the NBME and you will save yourself the headache of wasting incredible amounts of time doing stuff that doesn't even make you a better dentist, just because you are deathly afraid to drop one spot in the rankings.