Why can't doctors be more like dentists?

An interesting question from Curt Whitaker in the pages of the Concord Monitor:

Why does my dentist insist that I come in regularly, while my doctor's office only reacts when I call with a complaint?

And why is my dentist always so chipper, and my doctor seemingly hassled?

We may be about to launch into a brave new world of health care and, frankly, just about anything has to beat the weird system that we have now. But before we federalize, universalize or standardize health care, it seems worth asking: Why can't doctors be more like dentists? (more)

I don't hear all that many calls to "reform the dental system".