Yes, grades are not everything, but most if not all dental schools will rank academics as their number one priority in deciding who gets the interviews. Dental school is challenging! Day 1 you are blasted with a firehose of facts, knowledge, and advice. It gets easier, and almost everyone makes it through, but they want to make sure you can handle the curriculum without losing your mind or quitting. Of course, dental schools will have tutors and student resources to help you in the process, but they expect you to take initiative of your academics. Having a track record of good grades in undergrad is the best gauge they have to know what student you will be.
So what if you have some bad grades, are your changes for dental school over? Not necessarily. Your overall GPA and your trends in grades are factored in. If you had a rough couple semesters adjusting to undergrad, but you picked it up strong in the end, they'll recognize your persistence and ability to change your study habits. This could even be a plus if you say it the right way! And if you had one BAD grade that you feel is weighing you down, it's not. My interviewer for dental school asked me about a "D" on my transcript and what I learned from it. I learned that the best response you can give is to say that your grades don't define you. Nobody will understand the life factors happening at a certain time and you don't have to explain those to anyone either. If that "D" is sitting in a sea of A's and high B's then you are resilient and you realize a low grade is not a catastrophe. You might get a bad grade in dental school too, and admissions committees will want to know that you can bounce back fine.
It honestly doesn't matter what you choose, but have some other passions outside of dentistry and immerse yourself. Step up and be a leader where you feel you can help. Challenge yourself in hobbies or activities that sound fun and interesting. Undergrad is full of opportunities and you should embrace those years of trying out what you want.
But also, don't make the mistake of spreading yourself so thin that you become too stressed to do anything whole-heartedly, or that you don't have energy to study and your grades start slipping. Extra-curricular involvement and maintaining grades is such a fine art, I'd be lying if I said I've mastered it. It is really difficult to turn down activities, especially when you have leadership involvement in them, to focus on an upcoming test. If you recognize that you're not achieving the grades you know you can because your schedule is feeling too heavy, take some time to reflect. If you are having trouble balancing your time and feeling stressed, maybe talk to a counselor or your most level-headed friend. Extra-curricular activities should be your fun time, not what's weighing you down.
-Passion for dentistry-
This one is huge!! Why are you about to take four years of your life and pay half a million dollars to study the quirkiest possible field? Most schools have a minimum of 50 shadowing hours, and a little more than this would show you're not trying to just meet minimum requirements. You DON'T have to go crazy on the shadowing hours, however. I had a dental assisting job and racked up over 2,000 hours. I thought this would really set me apart...but it doesn't. The time I spent working took away from my academics, and I realized much later that putting my energy and time into a less important category was a mistake. DO shadow in different offices. The 50 hours in general dentistry is a must, but explore a few other specialties if you can so that you know what the dental field as a whole entails. Your passion for dentistry should be obvious in your personal statement.
-Commitment to service-
The reasons people pursue dentistry fall anywhere between wanting to devote themselves to helping others and wanting to make buttloads of money. You can agree the former is a more welcomed response. And I personally witnessed the ones pursuing dentistry for the financial appeal alone having a more difficult time with school, a few even dropping out of our program. Local and global service are some of the highlights of dentistry, and I believe you will enjoy the profession so much more if you embrace that. Community outreaches are a part of the dental school curriculum, and caring for patients in your school clinic are a must.
Taking part in your community and being in roles that show your empathy for others are STRONG positives for your application. And for you as a human being in general.
No matter how you end up spending your time in undergrad, when it comes down to writing your application, HAVE SOMEONE PROOFREAD IT, preferably a student advisor or someone from the career center if your school has that. I can not stress the importance of proofreading enough. It is not a comfortable experience watching someone edit and rip apart your resume and personal statement in front of you, I get that. When I applied for my orthodontics residency, I had 11 versions of my personal statement and 12 of my resume. I thought my version 1 was great and ready to submit...and was practically traumatized by the entire paragraphs crossed out of my statement. When I had my final versions written up, I was so grateful that I went through the WORK of editing. What worked for me was having weekly meetings with my student advisor to keep me on track with writing, and she also helped me stay on schedule for submitting my applications. Applications are exhausting, find someone who can help ease that stress early and be on your team. It'll make the process much more bearable.
BEST OF LUCK!!!!!