Toothbrushes are grody

July 17, 2005 11:54 AM

Why don't our tootbrushes make us ill? They sit out all day with our mouth germs and lord knows what else lingering there. Does toothpaste have anything to do with this?
posted by schoolgirl report to health & fitness (28 comments total)

Toothpaste is basically just soap and a little sodium fluoride. My guess is that there are two factors here:

1. Your mouth isn't the greatest path of infection. There's lots of stuff in there (and further down in the digestive tract) that will easily destroy most potential pathogens.

2. Every time you brush, yes, you're inocculating the brush with some random mouth germs, but those germs are not pathogenic as such (they live in our mouths without hurting us). The toothpaste scrubs off a lot of whatever's growing on the toothbrush anyway, and the end result is that there isn't really much going on on the toothbrush compared to any other non-sterile item that you put in your mouth.
posted by rxrfrx at 12:08 PM on July 17, 2005

How many of those germs die when the brush dries, anyway?
posted by hototogisu at 12:23 PM on July 17, 2005

It seems like the real question this hits on is: "Why are we afraid of things that sit out all day?"

Our society doesn't give our immune system all the credit it deserves.
posted by odinsdream at 12:32 PM on July 17, 2005

You're scared of your toothbrush? Think about where the stuff we eat everyday has been.
posted by trevyn at 12:37 PM on July 17, 2005

There are two issues here:

1. Much like your teardrops, your saliva contains a number of enzymes, some of which kill off foreign bacteria (e.g. lysozyme)

2. Your mouth contains a native flaurae of bacteria, such as those which give rise to plaque and bad breath. While aesthetically unpleasing, their numbers help keep foreign bacterial populations from taking hold

So your toothbrush can make you ill if it carries harmful bacteria and either your immune system is weak, you have a dry mouth, or the usual harmless bacteria aren't present. You may notice, for example, that you gargle with antibacterial mouthwash too much, you'll be more susceptible to sore throats.
posted by Rothko at 1:02 PM on July 17, 2005

Toothpaste is really detergent and fluoride, not soap and fluoride. Detergent does disrupt membranes - the sodium dodecyl sulfate we use for that purpose in the biochem lab is a slightly purified version of the sodium lauryl sulfate (or 'laureth') that is in the toothpaste. (Interesting trivia: the industrial chemist who named that mix of detergents named it after his daughter, whose name was Laurel or Lauryl.)

Anyway, disruption of membranes offs a lot of bacteria, and fluoride isn't particularly good for them either; mouth bacteria also prefer a certain pH. But think of this: bacteria need to eat, or else they must needs stop dividing. You want to see/smell something foul, dip your toothbrush in sugar before heading out the door in the morning. Just don't brush with it afterwards.

More trivia: The acid that causes a lot of tooth decay is created by a strain of a particular bacteria, and there's a company out there that will inoculate your mouth with a genetically-engineered strain of that bacteria which does not produce acid and can out-compete the acid-producer. If this catches on, someday soon you may kiss someone and be free of tooth decay for the rest of your life.
posted by ikkyu2 at 1:06 PM on July 17, 2005

there's a company out there that will inoculate your mouth with a genetically-engineered strain of that bacteria which does not produce acid and can out-compete the acid-producer

That's fascinating on a number of levels. Link?
posted by sennoma at 1:09 PM on July 17, 2005

lord knows what else

It was probably on MeFi that I read about (some TV show?) testing a toothbrush for fecal bacteria. Yup, they're there. The brand-new toothbrush in the closet, never opened? They were there too. The cooties/no cooties divide is not a good model.
posted by Aknaton at 1:18 PM on July 17, 2005

The TV show Aknaton is referring to, is probably "Myth Busters" on Discovery Channel. They did a few tests with toothbrushes in bathrooms.
posted by Narnia at 1:46 PM on July 17, 2005

When I was in High School I knew a girl who when she was sick would suck on a lollipop for a while and then put it back in the wrapper. Then when she wanted to get sick again she'd take out the lollipop again and suck on it.

I can't imagine this would have worked, but she seemed happy with her system.
posted by duck at 2:45 PM on July 17, 2005

ikkyu2- that all seems like a silly bunch of semantics. if you want to get specific, i'd say that "detergent" is a broad descriptor and "SDS" and "soap" are subsets of "detergent" that may or may not mean the exact same thing.
posted by rxrfrx at 3:12 PM on July 17, 2005

And lauryl in Sodium Lauryl Sulfate (or laureth, short for lauryl ether, in Sodium Laureth Sulfate) isn't named for anybody's daughter. It's named from lauric acid, aka dodecanoic acid, which is so named because it was first isolated from bay laurel (Laurus nobilis) trees.
posted by tiny purple fishes at 3:43 PM on July 17, 2005

I would say that anything that'd really infect your mouth is unlikely to be living on plastic bristles which you wash every day. You do wash your toothbrush everyday, don't you? I can't not wash it before every use.

In any case, brushing your teeth is likely to remove more problems from your mouth than it will introduce to it, especially if you rinse thoroughly afterwards.
posted by wackybrit at 4:26 PM on July 17, 2005

Why don't our tootbrushes make us ill?
Because we rinse them with water, then with peroxide after brushing? Well, some of us do.
posted by Kirth Gerson at 4:28 PM on July 17, 2005

I'm going with the awesome immune system answer. I don't wet my brush before I brush; I live in New York and bite my nails, so you can imagine what makes it into my mouth and you know what? I get sick a lot less often than other folks. Why? Because my body is a germ-fighting ninja, that's why.
posted by dame at 4:50 PM on July 17, 2005

why would it make you ill?
You only put it in your mouth(I hope). So anything on your brush is already living in your mouth.
and I would think your mouth would be a much better place to grow then your tooth brush, which would dry out pretty quickly, compared to your mouth that is warm and damp 24/7.
posted by Iax at 10:15 PM on July 17, 2005

Because my body is a germ-fighting ninja, that's why.

I wish enough people understood this that I'd never see another jug of antibacterial soap in someone's bathroom.
posted by knave at 10:32 PM on July 17, 2005

At uni a couple of weeks ago I heard a lecture from a pathologist about bacteraemia (the presence of bacteria in the blood). She said tooth brushing is associated with an up to 26% chance of bacteraemia, while for even normal chewing the chance ranges from 17-51%. The vast majority of times it is transient and is cleared by the body's immune system in less than 30 minutes.

I don't know anything about toothpaste, but I'm going to second everyone who said that the immune system's role is the most important.
posted by teem at 11:41 PM on July 17, 2005

ikkyu2, you're killing me with the wait! Link it up, please. /me would give his right arm to not get his 10th or 11th (or whatever number will be next) filling at only 26... The last four in a row made me want to just rip the damn teeth out.
posted by shepd at 12:26 AM on July 18, 2005

Why don't we have this anti-tooth decay bacteria yet? Only articles I found listed promising results back in 2000. This is clearly a hush-hush cover-up by the corporate toothpaste monopoly, who bought the patents and are keeping this all under wraps to preserve their profits.

Cavity Fighting Bacteria (About.com)

HealthMantra.com

University of Florida
posted by sophist at 1:20 AM on July 18, 2005

Here are the genetically engineered Strep mutans people.

tiny purple fishes: now that I think of it, that story about lauryl sulfate might have come from a Wallechinsky and Wallace book - the two I was unfortunately exposed to were People's Almanac and Book of Lists. More urban legends and outright falsehoods than you can shake a stick at - I wish I could globally wipe everything I "learned" from them.
posted by ikkyu2 at 1:21 AM on July 18, 2005

Why don't our tootbrushes make us ill?

Because they sit out all day with our mouth germs and lord knows what else lingering there, thus when we brush our teeth, the immune system is kept on its toes by these pitiful little bacterial incursions, so that when some really nasty baceria comes our way via a bleeding scrape on the knee filled with dirt and animal droppings from where it hit the ground, the bacteria don't stand a chance against the well-drilled all-veteren battle-hardened immune system.

People who obsess about hygene are the sickest unhealthiest people I know. I initually assumed, as they do, that they obsess over bacteria because they were so prone to getting sick, but now I suspect it's the other way around.
posted by -harlequin- at 1:30 AM on July 18, 2005

Great answers all, thanks much. And for reference, I'm not obsessed about hygene (hair and shaving products, maybe). I've just been curious about this for a long while, particularly when a cold makes the rounds of my family. Sounds like I need to give my immune system a bit more credit.
posted by schoolgirl report at 5:17 AM on July 18, 2005

I wish enough people understood this that I'd never see another jug of antibacterial soap in someone's bathroom.

Damn right. I hate that stuff -- the people who market it to the general public should be locked up for endangering the nation's health. (For those who aren't aware: if you don't thoroughly scrub your hands for long enough to kill all bacteria, as doctors are supposed to [but apparently often don't, or so I hear], you're just rewarding the tougher bacteria and helping breed strains that can resist our current antibacterials. So don't use it!)

that story about lauryl sulfate might have come from a Wallechinsky and Wallace book... More urban legends and outright falsehoods than you can shake a stick at - I wish I could globally wipe everything I "learned" from them.

Yeah, those two should be locked up too. By the way, great (first) comment, ikkyu2!
posted by languagehat at 7:32 AM on July 18, 2005

MetaFilter: My Body Is A Germ-Fighting Ninja
posted by matteo at 8:24 AM on July 18, 2005

There's a 2004 New York Times article on Oragenics. They just started Phase I trials a few months ago, and they're publicly traded now. (AMEX:ONI) So I bought a few shares to cheer them on. :)
posted by trevyn at 10:48 AM on July 18, 2005

Your mouth is a better environment for those germs to flourish (warm, moist, etc.) than the toothbrush
posted by winston at 1:33 PM on July 18, 2005

As an aside: This reminds me of my sister seeing a fashion shot in a magazine of a girl wearing trousers made from (unused) sausage skins. "That's so gross! That's disgusting!" she said. I wasn't bothered by it, and said "How can that be gross - I would have thought putting sausage skins in your mouth is far more intimate than wearing them".
A few weeks later, she declared herself vegetarian.
I'm not sure if there was a connection. :)
posted by -harlequin- at 4:02 PM on July 18, 2005