honestly bme was one of the best things i've done. sure it may be harder, and you may learn some irrelevant information to dentistry (i just took a fluid dynamics midterm now, when am i ever gonna use that huh?) but i think i learned critical skills in the major. it teaching you to think in a different way, and tackle problems differently. and honestly, after bme, every other disciple (except for maybe computer science) becomes pretty easy to grasp. so i'd suggest it, even though it may be harder. and its helps make you a distinct applicant...many of my interviewers brought that up during the interview, and they were interested in an applicant with a slightly different background. so go for it. its good for you.