Yes, as was stated the #1 rank is in NIH grants. Michigan dental has consistently been in the top 3 or 4 for the past several years for research funding. What that means is that they have top quality scientists. ALSO, if you look at the faculty there, alot of the researchers are DDS/PhDs. The head of the perio dept is a DDS/PhD who studies hormonal control of bone regeneration. The head of the pediatrics department works on tooth regeneration. So it's still a good school.
HOWEVER, when you're picking a dental school, you need to pick what's best for you as an individual. That's going to vary from person to person. See what place makes you happy. THAT'S what's most important here.