So this system is based on the merit of past graduates?
I hate to bring "school rankings" into this discussion... But, I can understand consistently bringing students in from top tier undergrad schools, I don't quite get the reasoning behind feeding from lower tier schools.
I don't understand what school rankings have to do with it. If dental schools have observed that certain undergraduate institutions have a pattern of producing successful dental students, then who cares how that institution is ranked? Does it matter if it's not a top 20 school? All that matters is that you have a set of students who can do well in dental school.
I'm turning this into a rankings discussion for a second, but I think rankings are crap and people put too much emphasis on it. I'm using US News here because I believe it's a commonly used ranking system, and I think other rankings use similar criteria and have similar rankings as US News.
Schools are ranked based on inputs - the high school GPAs/SAT scores of incoming students, the level of education of their professors, how much money alumni donate to the school, what other academic institutions think about the school, what kinds of financial resources are available, graduation and retention rates, quality of research produced by professors. This is all listed on the US News website. However, schools are NOT ranked based on outputs - acceptance rates into graduate programs, performance on exams like DAT/MCAT/LSAT/etc, employment rates immediately after graduation, the average income of their graduates, etc.
Students who go to top-ranked schools don't necessarily get a better education because university prestige is mostly based on the research the university generates, not on academics. And looking at the criteria that US news uses for its rankings, how many of them actually reflect the quality of education the students receive? Studies show that students who go to small liberal arts colleges do just as well or better than students from top-ranked schools on admissions tests. The top 4 or 5 schools who have the highest percentage of students going on to receive PhDs are all small, lesser-known colleges - only one of those schools is ranked in the top 50 by US News.
I wouldn't put much stock into rankings and name. Dental schools apparently take it into consideration, but I wouldn't be surprised if they have their own system for ranking schools.