Is Flossing Conventional Ignorance?

I saw an anecdotal study online recently which boiled down to “I lied to my hygienist about my flossing, and they couldn’t tell I was lying”. I love the energy exploring if conventional wisdom is actually useful, as well as the effort to actually put forth an investigation (yay citizen science!). Not to be a hater & poo-poo their efforts, but I do feel like their methodology might not be checking what is claimed.

Hygienists have to see dozens of patients a week, and the vast majority of them will not floss¹. If they’ve been trained that flossing is good for people to do, and it’s part of the spiel they have to give out, I believe the previous experiment is only activating the default response of “you should floss, naughty patient”, and it doesn’t seem like it is checking if they can truly tell. I don’t believe they are incentivized to spend the energy on a lying patient to find out the truth.

From what I’ve read, if you want people to give their full efforts on a problem, you gotta put real stakes on it. Might it be a better experiment for the patient to run if we activate loss aversion in the hygienist? They could say “here’s $25 dollars - I either never flossed, or flossed every day for the last 6 months. If you guess wrong, you lose the $25, else you keep it.” This removes the “blind” portion of the study, but I feel like it pushes people to try to give an accurate estimate, rather than just trotting out the default response.

Are we actually testing what we think 🔗︎

Even if you use that tweak to the methodology - there are still pretty major flaws with this approach of 1 mouth, 1 hygeinist. Are we actually testing if flossing makes a difference, or are we testing…:

• The skill of that particular hygienist at detection, or if there are confounding variables at their office that day (e.g. did they lose a lot of sleep from a crying baby? Have food poisoning?)
• How well your mouth responds to flossing? Maybe your teeth naturally don’t store anything in-between. In the comments of this article on a possible bacterial solution to cavities , it suggests there is a spectrum of mouth types for disease resistance, which seems like it would be a huge component of this flossing experiment.
• Something else entirely?

I applaud the effort to double-check a piece of our conventional wisdom and make sure it holds up, but I think we can do even better.