OK. I just did a predents.com search, and out of 16 students (who interviewed at UCLA, are Cal residents and are class of 2010 to be) 4 went to UCLA for undergrad. It's 5 out of 25 in class of 2011.
Thus, knowing that it's about 20~25%, UCLA undergrads are not specifically overrepresented in predents.com profiles, and the school usually interviews about 120 in-state students, we can assume that about 24~30 people from UCLA undergrad are invited for an interview at UCLA School of dentistry every year.
Of course I know that my conclusion can be wrong if many people lied on predents.com.
Btw, unlike I previously stated, I also found that there are many UCD and UCB students getting interviewed at UCLA.