Even if there were something truly "special" about the three Ivy League dental schools, attending one is indicative of the quality of DENTAL SCHOOL APPLICANT you were, not the quality of DENTIST you become. In all reality, regardless of where you go, you graduate with just enough knowledge/experience to not be dangerous. If graduates of Harvard, Columbia, and UPenn really do have an advantage in residency applications it's because program directors recognize that quality dental school applicants likely go on to become quality dental residents. An individual with a 3.7+ GPA and 24+ DAT score will almost certainly excel in dental school, regardless if they attend Columbia or the University of Florida, and they will likely also excel in training beyond dental school. So, it's not really hard for PD's to control for this school name variable. They just need to request your DAT score and undergrad GPA, and many programs already do. If I were a program director and I had an applicant from the University of Oklahoma with a 3.7+ undergrad GPA and 24+ DAT score, I would recognize this individual very likely turned down some expensive "prestigious" dental schools. In my mind then, academically there is nothing separating them from a Harvard grad. But, that Oklahoma grad might have a bit more common sense, in my opinion.
Big Hoss