Toothpaste

So, the other week I was in the store pur­chas­ing some tooth­paste. Now tooth­paste, at least in Amer­i­ca, is a great exam­ple of that phe­nom­enon of a huge num­ber of indif­fer­en­ti­at­able choices you often get when shop­ping at a typ­i­cal gro­cery store. There are maybe a dozen brands of tooth­paste and each brand has maybe a dozen prod­ucts all adver­tis­ing slightly dif­fer­ent advan­tages in the realm of tooth care. One tube of tooth­paste offers defense against cav­i­ties while another adver­tises that it will pre­vent plaque build up. Now, never mind the fact that the default expec­ta­tion is that all brands of tooth­paste will help pre­vent cav­i­ties, there is really no way for the casual shop­per to really eval­u­ate the claims of these dif­fer­ent products.1 If one uses one brand of tooth­paste for a year and never gets a cav­i­ty, there is gen­er­ally no way to know if it was that tooth­paste which pre­vent­ed, or if any brand would have done.

Now, I am cog­nizant of this issue and usu­ally just buy the cheap­est tooth­paste available.2 I typ­i­cally assume that most brands of tooth­paste are actu­ally pretty sim­i­lar and that it does­n’t mat­ter which I choose. Any­way, while shop­ping for tooth­paste the other week, the thought occurred to me that this assump­tion was, in fact, an assump­tion and that I could prob­a­bly check whether this was the case. So I took a moment to look at the ingre­di­ents list of a few pop­u­lar brands of tooth­paste.

I noticed right away that they all seemed to have the exact same soli­tary active ingredient: sodium fluoride. “Ah ha!” I though, “I’m more right than I know!” But then I looked again and noticed that there was also an inac­tive ingre­di­ents list and that this list did vary from tooth­paste to tooth­paste. It var­ied sig­nif­i­cant­ly. Now, these are inac­tive ingre­di­ents so it was prob­a­ble that they had no effect on the effi­cacy of the tooth­paste, but you never know until you check. So I went a lit­tle over­board and pho­tographed the ingre­di­ents list of every brand of tooth­paste in the gro­cery store that day and com­piled a list of every ingre­di­ent that I found included in some brand of tooth­paste. I then researched each of these ingre­di­ents to deter­mine what the prob­a­ble usage was. I’ve com­piled the full list as well as there prob­a­ble usages into a list (at­tached to the end of this blog post).

There were actu­ally five active ingredients:

sodium fluoride              tooth-hardener
sodium monofluorophosphate   tooth-hardener
stannous flouride            tooth-hardener
potassium nitrate            anti-sensitivity
triclosan                    antiseptic

No tooth­paste used all five ingre­di­ents at once but some had two. Typ­i­cally one of either sodium fluoride, sodium monofluorophosphate, or stannous flouride was present with, option­al­ly, either potassium nitrate, or triclosan as a sup­ple­ment. Now, if you’ve ever been to the den­tist, you’ve prob­a­bly been through the ‘flu­o­ride mouth­wash’ rit­u­al. If not, per­haps you’ve heard of flu­o­ride being intro­duced to the water sup­ply. Either way, the actual chem­i­cal being used was likely sodium fluoride. If not, it was prob­a­bly either sodium monofluorophosphate or stannous fluoride. Either way, the pur­pose of flu­o­ride, in den­tal care, is to harden teeth by con­vert­ing apatite, a cal­cium com­pound that is one of the main com­po­nents of your teeth to fluorapatite, which is a ver­sion of apatite that is more resis­tant to the acid pro­duced by the microbes that live in your mouth. 3

So, the obvi­ous con­clu­sion is that the main action of most tooth­pastes is just flu­o­ride ther­a­py. You can rinse with flu­o­ride mouth­wash to get the same (ac­tu­ally stronger!) effect. How­ev­er, there is more. Potassium nitrate, also known as salt­peter, is a chem­i­cal com­monly used in the mak­ing of bombs and incen­di­aries. When applied to sen­si­tive teeth, appar­ently it crys­tal­izes over the exposed nerves and helps to pre­vent those nerves from get­ting trig­gered. Potassium nitrate was found in most tooth­pastes adver­tised as being for sen­si­tive teeth. Not all included it though and those that did­n’t used stannous fluoride.

The final active ingre­di­ent is triclosan. This is actu­ally an antibac­te­r­ial and anti­fun­gal chem­i­cal. It’s present in a lot of antibac­te­r­ial soaps. It’s pur­pose in tooth­paste is to pre­vent and fight infec­tions, such a gin­givi­tis.

That’s it for the active ingre­di­ents. There is still the prob­lem of the inac­tive ingre­di­ents. It seems that the major­ity of inac­tive ingre­di­ents are some vari­ety of ‘thick­en­er’, ‘foamer’, or ‘gelling agent’ to give the tooth­paste its typ­i­cal ‘paste’ qual­i­ty. There was a lot of vari­ety in what thick­en­ers were used, but I doubt that they made much of a dif­fer­ence in the qual­ity of the tooth­paste. After that, many of the ingre­di­ents were col­orants, arti­fi­cial sweet­en­ers, or preser­v­a­tives, none of which should have an effect on tooth health either.

So it would seem that I was cor­rect in my first assump­tion that the inac­tive ingre­di­ents did­n’t mat­ter, except that I did across a small list of ingre­di­ents that actu­ally weren’t thick­en­ers, col­orants, or sweet­en­ers. These chem­i­cals were:

calcium peroxide           tooth whitener
cetylpyridinium chloride   antiseptic
cocamidopropyl bedaine     antiseptic
hydrated silica            abrasive
mica                       abrasive
sodium bicarbonate         bleaching agent, antiseptic
sodium hexametaphosphate   anti-staining, tarter prevention
sodium hydroxide           cleaning agent
sodium lauryl sarcosinate  cleaning agent, polishing agent
sodium lauryl sulfate      antiseptic
zinc citrate               anti-plaque
zinc phosphate             dental cement (glue)

So how about that? Active, inac­tive ingre­di­ents. Two of these ingre­di­ents are hydrated silica and mica and are used as abra­sives in attempt to help scrape plaque off teeth. Per­son­al­ly, I thought that that was what the tooth­brush was for, but per­haps this helps. Calcium peroxide is used to whiten teeth with­out actu­ally bleach­ing them. Appar­ently it replen­ishes the cal­cium in the teeth. Other chem­i­cals, such as cetylpyridinium chloride and sodium lau­ryl sulfate are anti­sep­tics just like triclosan that kill microbes and hope­fully pre­vent gin­givi­tis. Some of the chem­i­cals, such as sodium hydroxide are cor­ro­sive clean­ing agents (sodium hydroxide is used in drain clean­er­s!) and seem like they might be overkill for your teeth.

So all that is very inter­est­ing and I now have a much bet­ter appre­ci­a­tion for what goes into tooth­paste and how it’s sup­posed to work. I sup­pose that if I could pick my ideal tooth­paste, it would con­tain stan­nous flu­o­ride, tri­closan, and cal­cium per­ox­ide as my teeth aren’t sen­si­tive and I’d avoid some of the more caus­tic chem­i­cals as I sus­pect they might be counter pro­duc­tive, (though I hon­estly have no idea if they actu­ally are.) In the end though, most tooth­pastes seem to do mostly the same thing with slightly dif­fer­ent ingre­di­ents, but with sig­nif­i­cant vari­eties in for­mu­la­tion. At least now the adver­tise­ments on the pack­ages make a lit­tle more sense to me.

Full Ingredient List

active

inactive

  1. With the exception of anti-sensitivity toothpaste where I imagine a person with sensitive teeth could tell if the toothpaste helped. ↩
  2. This is Aim brand toothpaste in my local grocery store. ↩
  3. It appears that sodium monofluorophosphate and stannous fluoride are more effective than sodium fluoride. ↩

Last update: 22/10/2015

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