Understand the mission statement of UCSF. They are a good enough school that they can be picky about who they admit and it will always be students who are willing to give back to the dental community and improve dental culture away from the 'instagram dentists'. These are the people they look for and thats why youll see them rejecting high stat students. And dont be nerved by the drop in class size. There are multiple people who go accepted in UCSF who also got accepted into other top programs/are oos and will drop their spot.
As far as the interview is concerned, go online and research what entices you about UCSF. If its their research (only use this if you are doing research as an undergrad or it feels fake), their commitment to community dentistry or their campus culture/clubs etc. Think about what entices you to dentistry and try to stay away from the same old answers like like to be your own boss or working with your hands etc. Prepare for the interview but dont memorize answers. Its very easy to know when someone is reciting off a script so jot down key points you want to touch upon in an answer but dont write an answer down. Practise in a mirror and make sure you speak slowly and without saying to many 'uuuhs'. And finally when they start the interview, they will you to tell them about you. Thats your gateway into controlling the direction of the interview and what sets good applicants from great. Make a small introductory list that showcases your important points that you want the interviewer to know. Whether you do research, have participated in certain programs, internships or real life struggles; this is your moment to tell them and then later on they will ask you about them.
Hope this helps. Good luck for your interview.