Who you aiming it mostly at Dentists? Doctors? or other allied health professionals?
If mostly dentists - then blue one definitely!
If you are aiming for the wider health and medical market - I'd go for a more generic... Doctors and other health professionals probablyl won't jump at a Tooth.
Just my thoughts anyway - as I'm in the wider allied health industry.
Blue, I like the graphic. As for the clarity, I don't think it necassarily needs to be perfectly discernible at first look, but that's just my opinion - I like it as it is
Without a doubt blue.
If it's for doctors as-well, consider a more generic icon. Perhaps you will want to supply two icons, one for docs and one for dentists. If you have an installer see if you can set the applications icon there (I'm sure many people won't like this idea).
Perhaps you'll want to keep the grayscale icon for update packages?