First, if there is anyone who is going into dentistry who cannot handle it, then they are in the wrong profession.
Next, looking at disgusting teeth sure beats having to look at and probe the southern orifices. Not to offend the ladies here, but from what a couple OB/GYN's I know have said - I couldn't handle some of the disgusting things that women have to deal with vaginally. It would take the mystique away from it and I probably lose some interest in my wife because of it.