Why was Richard Feynman against brushing your teeth?

Brush your teeth several times a day

As with almost every case related to human physiology / biology: it depends.

Brushing has been shown to remove food particles that lead to decay. However, brushing your teeth can also damage your teeth and gums if you use a stiff-bristled brush or brush too vigorously.

The general consensus among dentists seems to suggest that you should brush gently after you eat. Although toothpaste is not required for all sessions. And when you've eaten something sour, it's best to wait.

According to Peter Heasman, professor of periodontics at Newcastle University's School of Dental Sciences, the correct practice is to brush with 150 grams of pressure twice a day for two minutes - the equivalent of holding an orange.

In addition, regular dental care (and its associated benefits, which are well documented across the entire field of dentistry) can lead to better heart health.


Ideally, I want something evidence-based rather than describing the advice various agencies give.

Larian LeQuella

I would argue that the entire field of dentistry is the proof. I'm sure you don't need a quote to say it hurts to put an ice ax through your head, or is that a bad idea? Dental care has achieved the same level of "obviousness". The areas where good advice can be given are those identified in the answer (i.e., the right procedure and timing).


For me, speaking directly about what is important in evidence would mean stepping out of character a little. That leads me to point out the conflict of interest: Dentistry makes money selling various products. Few dentists run their business on a model that would benefit them if their patients had good teeth. Given this conflict of interest, it is important that dentists provide evidence of their claims.

Larian LeQuella

The literature is available on every website that shows how food particles allow bacteria to deposit sugar on your teeth and that sugar and bacterial waste are bad for your tooth enamel. Not to mention the enzymes in your saliva that start the digestive process and also work on the food particles on your teeth. While I hate the saying "common sense" this really is a case for it. Give bacteria food and a comfortable environment, they will multiply and leave waste and do their thing.


@ Jim: This answer does not apply to controlled trials. This community has a standard that answers should be backed by evidence. The burden of proof rests on the person posting a response. Larian argues that he is fulfilling his burden by indicating it by making an argument of authority. Controlled experiments are not necessary as brushing your teeth is a given.