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The dentist and the statistician

Kaiser reports his conversation with his dentist:

Dentist: You need a deep cleaning.

Statistician: I don’t believe in deep cleaning.

Dentist: I only manage to clean the exposed part of the teeth. In your X-ray, we can see tartar buildup underneath the gums. Your teeth will fall out eventually if we don’t clean it up now.

Statistician: My teeth feel fine, in fact, the best in years. I don’t like the cost-benefit tradeoff of deep cleaning. . . .

The funny thing is that I don’t act like a statistician when I go to the dentist. In particular:

1. I believe whatever my dentist tells me.

2. When I switch dentists, the new dentist typically gives me completely different advice than I received from all the previous dentists.

I’d like to think that I’m practicing what I. J. Good calls Type 2 rationality–that is, the rationality that tells me that I’m not realistically going to make a fully rational decision in this area, hence it’s most rational to make a decision using a fast and frugal heuristic (in this case, trusting whatever my dentist tells me).

When considering my long-term happiness and comfort, however, maybe I’d be better off putting some more time into research on dentistry and less time on . . . I dunno, blogging? For some reason, I’m full of confidence in evaluating all sorts of arguments about social science and causality, but I’m completely intimidated when it comes to something such as dental care that affects me personally.

11 Comments

  1. Pat says:

    I'd say you start from the prior belief that your dentist knows what he's talking about, rather than implicitly assuming he's just some random dude.

  2. dWj says:

    The sort of person who becomes a dentist is disproportionately likely to be someone who values clean and healthy teeth higher relative to, e.g., comfort, sweet food, and convenience than the average person.

  3. dWj says:

    (The sort of person who leaves comments on a statistics blog is disproportionately likely to be a numbers geek who is prone to forget to eat, let alone to brush his teeth, without being reminded by his fiancee. Or else this is just availability bias.)

  4. Jeremy Miles says:

    The author of The Underground Economist (possibly in the book of the title, or possibly in the column, I forget) said that he doesn't floss, against his dentist's advice, because the evidence suggests that flossing daily will result in (on average) 1 more original tooth in old age. And that didn't seem worth it to him.

  5. Bob Carpenter says:

    You [Andrew] said the same thing about different stats methods recommended by different statisticians!

    While we're on the topic of dentistry, I just so happen to have built a hierarchical model of dental diagnoses from X-rays in R and BUGS (with some help from Andrew and Jennifer and Masanao).

    In your [Andrew's] case, I feel some responsibility, having recommended Dr. Gregory Hull to you! Mitzi and I love Dr. Hull. It seems more a matter of trust than anything else. I like Dr. Hull because he's great at explaining what he's doing and why. And he does all the work himself — how cool is that? But you're right that dentists have different philosophies — Dr. Hull's not as obsessed with "pocket depth" as my Pittsburgh dentist was.

    By the way, Dr. Hull recommended an oral surgeon who did a great job extracting a tooth I cracked on Mitzi's whole wheat bread (which, by the way, finally convinced her to make a loaf of egg bread using Andrew's recipe [which is pretty much a challah]). We'll see how they do on the post and crown coming up this year.

  6. Andrew Gelman says:

    Bob: The key is to take the challah out of the oven while it's still a bit gooey. But maybe you knew that already.

  7. Bob Carpenter says:

    We have different tastes. I like my baked good baked all the way through. We'll have to have you back for (a traditional) Thanksgiving — my grandma's recipe for rolls, the highlight of our Thanksgivings, is also very similar to your bread recipe.

  8. Steve Sailer says:

    When I had lymphatic cancer back in the 1990s, I did a lot of Internet research and eventually found a clinical trial in which I became the first person in the world with my form of non-Hodgkins lymphoma to be treated with what's now the gold standard, Rituxan, which went on to become the top grossing cancer drug in the world.

    So, doing Internet research on my health care may well have saved my life. Yet, my subjective recollection of it is that it was enormously emotionally painful to do the research, and I would still much rather just delegate my health-care decisionmaking to health professionals.

  9. Keith O'Rourke says:

    Steve – I have worked with chiefs of medicine and surgery at various teaching/research hospitals and thier take on personal medical issues was to find someone they trusted and ask them "just tell me what to do" – as you say "rather just delegate my health-care decisionmaking to health professionals".

    But Dentistry got into clinical trails much later than medicine and there probably is not good evidence for most of what currently done in practice. I sometimes discuss that with my dentist who largely agrees with me on that and then I largely just go along with what he suggests…

    Keith

  10. cb says:

    I proposed to my partner that I won't floss based on Jeremy Miles and the Underground Economist's insight. Her response was the study conducted by Hal I Tosis? Aren't economists known for the good breath?

  11. http://models.street says:

    I am a believer in dental care, I have a family history that includes several people with fairly problematic gum disease related problems. I tend to buy the idea that the deep cleanings do something useful, but I wouldn't have them done "frequently".

    Furthermore, number of teeth at death is not really the issue. The issue of most interest is how low level infection increases risks for cardiac disease, and may lower life expectancy overall, not to mention lower quality of life through general dental pain and bad breath. The evidence on the cardiac health stuff is not clearly causal though, I'd like to see a good review of the evidence actually. Anyone know of any?

    Most recently at the dentist after a cleaning they tried to sell me on some antibiotic treatment. I asked for the pamphlet, read it, and found that the "significant" reduction in pocket depth was about 0.1 millimeters on average between the treatment group and the people with just regular cleaning. Statistically significant, but not practically significant since the treatment cost was about 2 times the cost of an additional cleaning.