My dental school interviews were actually my first interview experience ever. I actually wrote down the answer for each question and would read it every few days and the morning of my interview/waiting room. After every interview I would add/revise my list and even my answers. Obviously I'm not going to memorize each answer, but it helps get your mindset in the right place and it helps you keep track of points you want to make. You'd be surprise with how many people walked out of interviews, blanking on a typical question and not knowing how to answer it. Know about the school, do your research and dress well(not too big/small and no funeral look). Funny enough how you feel in your clothes will affect your feelings, so put effort into it! Once you finish your first interview, you'll be fine after that.
I tried doing mock interviews with family and friends, but they went embarrassing bad. Funny enough, I did LOADS better during my actual interview. I guess I'm more self conscious with people I actually know. I was really nervous and my first interview was Uconn with two interviewers at the same time! which I thought went surprisingly well and came away with such a high. Yes, these people do have some power, but you're also interviewing them. Its a two way street and they're just strangers. I stopped doing mocks after my first interview and just looked at my sheet and practiced in my head. Be yourself and you'll be okay.
You got this far, your grades are there, your exam scores are done/will be done. Be happy with this special moment in your life. Show that during interviews. Show that you're happy about your choices and that you're confident.
Good luck!