Don't Listen To The 'Fifth Dentist'

Have you ever wondered about the “fifth” dentist? Maybe she works for Coca Cola. Maybe he works for Kraft, maker of Kool-Aid.

We all know the ads: “four out of five dentists surveyed agree that…” So, again, what’s up with the fifth dentist?

We don’t know, but the important thing is: we don’t care! The whole point of those ads is to impress upon us the massive consensus among experts. Four out of five sounds like a lot. It’s 80%. It’s a landslide. In fact, it’s a lot better than a landslide- conventionally defined as 58% or more.

We don’t care about the fifth dentist, and Madison Avenue knows it. They know that four out of five is enough of a consensus to use in their efforts to sell us stuff, such as particular gum, or toothpaste.

So consider the inconsistency, and arguably the hypocrisy, when we allow some isolated, rogue voice or lone dissenting study to cast all we know about climate change, immunization, or diet, into doubt. The consensus among experts about climate change, our complicity in it, and the general theme of what we should be doing about it is vastly greater than four out of five. The consensus among legitimate experts about the net benefit of vaccination, and its decisive non-contributions to autism, is very near to unanimity. The consensus among leading experts around the world about the fundamentals of good nutrition is in the same ballpark. 

But the very culture that sells us our toothpaste, whitening strips, and sugar-free gum with the iron-clad argument that four out of five dentists are in favor, pretends that one iconoclast a controversy makes whenever there’s profit in it. And we- in a recurring display of collective, gullible, nincompoopery- seem inclined to buy both arguments. As in: “yes, we’ll take the gum, because- duh!- but no measles vaccine because you know what they say…

Wow. We get it wrong in both directions, again and again. Duped by statistical gibberish (which four, out of which five?), but impervious to genuine consensus and the relentless tilt of the weight of evidence. Talk about meeting the enemy and finding out it’s us. 

And that fifth dentist, who is telling us we can keep debating climate change; we can forgo immunizing our children; and we are utterly befuddled about the basic care and feeding of Homo sapiens, so we may as well enjoy the pepperoni pizza, doughnuts, and multicolored marshmallows as part of a complete breakfast.

And the Kool-Aid he is selling to wash it down. Good luck with those teeth.


Director, Yale University Prevention Research Center; Griffin Hospital

Immediate Past-President, American College of Lifestyle Medicine

Senior Medical Advisor,