4 ms·

That there are no randomized control studies is hardly surprising: nobody would ethically assign a person into the "no dental care" control group. I am reminde

That there are no randomized control studies is hardly surprising: nobody would ethically assign a person into the "no dental care" control group. I am reminded of the randomized control study they did on parachutes which showed that parachutes were useless. Of course, to ethically allow people to jump out of an airplane without a parachute, they made sure the jump was not more than a meter and a half off the ground. What that satirical study actually showed is that randomized control studies don't always make sense.

jerf 8y ago
The study page: https://www.bmj.com/content/363/bmj.k5094 https://www.bmj.com/content/363/bmj.k5094 The study PDF: https://www.bmj.com/content/bmj/363/bmj.k5094.full.pdf https://www.bmj.com/content/bmj/363/bmj.k5094.full.pdf
BeetleB 8y ago
>That there are no randomized control studies is hardly surprising: nobody would ethically assign a person into the "no dental care" control group. They're not saying "no dental care". They are saying "no dental floss", or "no fluoride toothpaste", or "no fluoride in water", or "brush once a day". The reality is that a significant percentage of the population falls into one of these three categories (I was surprised you could by toothpaste without fluoride, but you can - there's a market for it). And yes, while you can't do true randomization, you can compare dental outcomes between these groups. And finally, saying it's "unethical" is a stretch. It's not unethical if there is no good reason to believe these measures are good for health. Until there's a clear study, these all fall into the same category as other traditional/folk medicine. When I first went to my current dentist years ago, he said "Your insurance covers two cleanings a year, and we'll give that to you. However, I'll have you know that there's no evidence that twice a year is better than once" and he proceeded to tell me a bunch of other common dental practices, their origins, and the lack of studies on them. It reminds me of the whole 8 glasses of water a day belief, which until about 10 years ago was commonly promoted by doctors. Then in about 2005-2007, someone published a literature survey showing no studies had ever recommended 8 glasses with good reason. All my doctor friends knew of this survey and promptly stopped recommending it.
- BlackFly 7y ago
  I agree with everything you are saying. Let me rephrase what I was saying so you can see we more or less agree. The article is complaining that there are no randomized control studies and using this to conclude that there is little evidence to support flossing. They are simply disregarding other types of studies like the observational study you are pointing out have value. These observational studies show such clear benefits to flossing that directing a person to stop would be considered unethical. I am pointing to a more facile example where you would never imagine performing a randomized control study because it is obvious that the no treatment control is dangerously unethical. Doctors end up being susceptible to public misconceptions just as much as the general public. Not everybody reads original research or health guidelines. So someone hears that the official guide recommends 2.5 liters of water, with no mention of the accompanying note that most of this comes through ordinary food intake, and they misinterpret it as needing 8 glasses of water a day. That is the case for the 8 glass a day myth: no scientific study ever recommended it, but half readings of some literature seemed to imply it. If you like myths like those, read through https://www.snopes.com/fact-check/water-works-2/ https://www.snopes.com/fact-check/water-works-2/ especially when it gets to the diuretic effects of caffeinated beverages. I mostly learned about this when I started talking to foreigners about it and realized it just wasn't common knowledge outside of North America that caffeine causes dehydration.

jerf 8y ago

The study page: https://www.bmj.com/content/363/bmj.k5094 https://www.bmj.com/content/363/bmj.k5094 The study PDF: https://www.bmj.com/content/bmj/363/bmj.k5094.full.pdf https://www.bmj.com/content/bmj/363/bmj.k5094.full.pdf

BeetleB 8y ago

>That there are no randomized control studies is hardly surprising: nobody would ethically assign a person into the "no dental care" control group. They're not saying "no dental care". They are saying "no dental floss", or "no fluoride toothpaste", or "no fluoride in water", or "brush once a day". The reality is that a significant percentage of the population falls into one of these three categories (I was surprised you could by toothpaste without fluoride, but you can - there's a market for it). And yes, while you can't do true randomization, you can compare dental outcomes between these groups. And finally, saying it's "unethical" is a stretch. It's not unethical if there is no good reason to believe these measures are good for health. Until there's a clear study, these all fall into the same category as other traditional/folk medicine. When I first went to my current dentist years ago, he said "Your insurance covers two cleanings a year, and we'll give that to you. However, I'll have you know that there's no evidence that twice a year is better than once" and he proceeded to tell me a bunch of other common dental practices, their origins, and the lack of studies on them. It reminds me of the whole 8 glasses of water a day belief, which until about 10 years ago was commonly promoted by doctors. Then in about 2005-2007, someone published a literature survey showing no studies had ever recommended 8 glasses with good reason. All my doctor friends knew of this survey and promptly stopped recommending it.

BlackFly 7y ago
I agree with everything you are saying. Let me rephrase what I was saying so you can see we more or less agree. The article is complaining that there are no randomized control studies and using this to conclude that there is little evidence to support flossing. They are simply disregarding other types of studies like the observational study you are pointing out have value. These observational studies show such clear benefits to flossing that directing a person to stop would be considered unethical. I am pointing to a more facile example where you would never imagine performing a randomized control study because it is obvious that the no treatment control is dangerously unethical. Doctors end up being susceptible to public misconceptions just as much as the general public. Not everybody reads original research or health guidelines. So someone hears that the official guide recommends 2.5 liters of water, with no mention of the accompanying note that most of this comes through ordinary food intake, and they misinterpret it as needing 8 glasses of water a day. That is the case for the 8 glass a day myth: no scientific study ever recommended it, but half readings of some literature seemed to imply it. If you like myths like those, read through https://www.snopes.com/fact-check/water-works-2/ https://www.snopes.com/fact-check/water-works-2/ especially when it gets to the diuretic effects of caffeinated beverages. I mostly learned about this when I started talking to foreigners about it and realized it just wasn't common knowledge outside of North America that caffeine causes dehydration.