I'm guessing you mean University of California vs California State University, judging from your location. However, the following advice is sort of universal.
My two cents: dental schools don't care too much where you got your degree so long as you have good grades (oGPA, sGPA) and good DAT scores. I think the prestige of undergrad plays so small of a deciding factor that it doesn't really matter for all practical purposes from the perspective of the applicant. Just study hard, get involved in something dental related (e.g. shadowing, research, volunteering, etc), and enjoy college.
People from UC's get rejected and people from CSU's get accepted. The reverse is also true. Cream always rises to the top.