I've heard it said that dental applicants who majored in something other than Bio or Chem or Biochem are often looked at favorably for the fact that they have a broader range of interests or something like that.
Getting good grades should be your goal, always. Don't be wasting your money or your parents' money by doing badly. On the flip side of that coin, college is a time for many to grow and discover who they are and what they want from life. Some people need to take those chances and experiment with different crowds and even do badly in a course or two before they realize a few things about themselves. The important thing is that you use this college time wisely, which means you try your best in class, and you expand your horizons, discover yourself and mature. Don't let 4 years of undergrad be a blur of libraries and study sessions, but don't let it be a blur because of too many keggers. Strike a healthy balance. Allow yourself time to live but enough time to study. Finally, learn from your mistakes and try to rebound if you do crash. How you handle adversity is also something that is noticed by adcoms.
Best of luck to you as you embark on this new phase of your adult life.