Based on my interview & the interviews 4 of my friends had, the student interviews are generally more difficult than the faculty interviews. The faculty really does try to get to know you better & to find out if you're a good fit for the school; the students, however, try to find out if you're truthful about everything on your personal statement & how you would adapt to the rigor of dental school.
Questions I got asked:
Faculty: Why UNLV? Why dentistry? Tell me about yourself.
Student: Why UNLV? Explain to me the steps involved in an RCT. What are some common tools used in amalgam restorations? How will you manage your time while in dental school? How would you contribute to UNLV? What would you change about UNLV dental school?
Like what John Durian stated, it really depends on who you get. Some students are very laid back & some want to see how you do under pressure. Most important things to do: show your compassion for dentistry & just be yourself. I hope this helps, and I wish you the best of luck!