Friday, August 2, 2013

How Does It Work? Toothpaste

Unless you have very fuzzy teeth, there is a remarkably high probability that you use toothpaste. But what exactly is it about toothpaste that gets your teeth less disgusting?

The vast majority of toothpaste action is simply mechanical. Over half of the ingredients in any any given toothpaste are simply abrasives, designed to scrape the disgusting gunk away from your mouth. Aluminum hydroxide, calcium carbonate (yes, the same calcium carbonate that forms shells for marine life, snails and eggs), dicalcium phosphate, and silicon dioxide (otherwise found in sand, quartz, and diatom frustules), among others. As you brush your teeth, you simply scrape away the goop from your mouth.

This picture was totally not posed at all. 
Because toothpaste is mostly an abrasive, it is relatively common for people to use things like baking soda as a substitute. However, commercial toothpaste does have additional benefits.

One of the most notable benefits of toothpaste is the addition of fluoride (usually in the form of sodium fluoride). Fluoride is an anion, a negatively charged molecule. When the halogen fluorine picks up an extra electron, it becomes F-, the anion that matters for your teeth. Sodium fluoride, the most common way of getting fluoride in your toothpaste, is an ionic compound, meaning that it dissolves into sodium ions (Na+) and fluorine ions (F-). Of course, many other additives exist to direct fluoride to your teeth;  hexafluorosilicic acid and salt sodium hexafluorosilicate, for example, are the versions usually used in drinking water.


When fluoride is included in toothpaste, low concentrations of fluorine ions hang out in your saliva. This reacts with the calcium phosphate in your teeth, forming a mineral called fluorapatite. This process, called remineralization, can help fix a just-beginning-to-form cavity. It also interferes with the biological functioning of cariogenic (cavity-causing) bacteria such as Streptococcus mutans.

Triclosan, an antibacterial agent, is also a common toothpaste ingredient, serving to prevent both plaque and gingivitis. Some toothpastes will also contain detergents (such as sodium lauryl sulfate), flavorants, and additional remineralizers.

7 comments:

  1. Let me tell you a story.
    I just bought Lush Toothy Tabs (they were cheap and I had a gift certificate to finish). And then I was all pleased with myself because HEY SOLID TOOTHPASTE TABLETS! perfect for flights/lightweight camping/my purse when I'm in a tooth-neurotic phase!

    Except two things. First, they taste like monkey santorum. Second, THEY HAVE NO FLUORIDE ETC IN THEM WHATSOEVER - they're basically just pressed baking soda with a little bit of vanilla and mint flavoring (and I'm presuming monkey santorum). A dentist friend and I emailed Lush to be like, dude these are a great idea so why don't they have fluoride and stuff? And Lush straight up admitted: our customers are more interested in the "natural ideal" (i.e. they are fluoride-paranoid) than they are about cavities. Lush don't make any dentist-recommendable toothy tabs because they want to uphold their natural hippie image.

    Blurgh. Now, since this is becoming a rant, I might as well finish. If you are afraid of fluoride, fine. Maybe you are from Portland. Whatever, I don't mind. But if you're going to sell things as real toothpaste substitutes, fucking make it more obvious than just being all "la la la, well we ARE Lush after all!" And could someone else please make toothy tabs that are better because they are so patently a good idea?

    Also I do like plenty of Lush products, but when marketing trumps science, it always pisses me off.

    Rant complete.

    PS - Robyn, do you have an opinion on triclosan? I <3 fluoride but I avoid triclosan on environmental grounds, but you might be more informed.

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    Replies
    1. I agree with you 100%! I love the rose flavored toothy tabs - I use them in the morning, and keep some at work for tooth emergencies, but ALWAYS use a fluoride toothpaste before bed. Because fluoride.

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    2. The EPA has stated that environmental issues associated with triclosan likely aren't due to commercial use by the general public, but I can definitely look into it more for you.

      Also, you would think that Lush would make a fluoride version (so offering both fluoride and non-fluoride), regardless of the hippie-dippie-ness of their customers! I wonder if they are having issues with creating a solid version of a fluoride product? Given that sodium and fluorine atoms must dissociate in order for fluorapatite to form, maybe the level of dissociation that occurs in your mouth is insufficient for there to be a beneficial effect... (Obviously, this is only speculation!)

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  2. Does it matter greatly in which order you eat, drink coffee, and brush your teeth? I've heard so much contradicting information on the matter. I tend to eat/drink before brushing because I don't want bits of breakfast stuck in my teeth all day. However, I've read that food and acidic coffee weaken your enamel and brushing soon after can cause abrasion while the enamel is weakened. On the flip side, I also heard that a toothbrush abrades the enamel somewhat, so you don't want to eat too soon after brushing to allow time for remineralization. I'm curious if there's any science to support either of these claims?

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    Replies
    1. Honestly, I have no idea. I'll look into it!

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  3. Same dentist friend says he learned "spit don't rinse" with regards to tooth order of operations. (REVOLUTIONARY for me.) Another anecdote: I clearly remember solid prescription-only fluoride tabs when I was about 6 so I doubt it's a solid state/solubility problem, but a lot of very subjective variables in play there (geography, marketing). Interested in the triclosan findings.

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  4. I just stumbled upon your website, and I think it is perfect for me. Beauty for the critical minded, yay! People who're into beauty are mostly also into bullshit, as I've learned from all the hairdressers I've had.

    So all I wanted to say, nice to see a beauty website actually providing info which is sound from a scientific standpoint.

    Thumbs up to you!

    ReplyDelete

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