Does Arm & Hammer Toothpaste Really Neutralize Acid Better Than the Rest?

I've been a loyal Arm & Hammer toothpaste user for years, but as I walked through the toothpaste aisle the other day, I wondered...why am I paying an extra $2 for this toothpaste when it probably does the same thing as all these cheaper brands? Is Arm & Hammer actually making a difference for my teeth? To put its claim to the test, I conducted an experiment to see if it really neutralizes acid better than two of its competitors.

Chemistry and Safety Concerns

To start, let's take a look at some of the chemicals that are inside Arm & Hammer toothpaste and see how they work. The star of the show for Arm & Hammer seems to be Sodium Bicarbonate, which is really just Baking Soda. Sodium Bicarbonate is a natural mineral, so humans have been using it for thousands of years, and it is a fairly strong base, as we know from its reaction with vinegar made famous by countless elementary school science fair volcanoes. For teeth, it's good to have a basic substance like Sodium Bicarbonate, to neutralize the acidic surface stains on your teeth and prevent acidic substances from eating away at the enamel that protects your teeth.

Baking Soda - NaHCO₃

Sodium Fluoride - NaF

Tetrasodium Pyrophosphate -  Na₄O₇P₂    

Next up, let's take a look at one of the lesser known chemicals that jumped out at me when looking through the ingredient list - Tetrasodium Pyrophosphate. This chemical is responsible for tartar control. Tartar is the term for the hard Calcium and Magnesium deposits that can wind up on teeth, which lead to major problems like gum disease and cavities. The tetrasodium pyrophosphate chemically prevents these hard mineral deposits from forming on your teeth, which seems all well and good. BUT...as is often the case, its reactivity can potentially present some problems as well. In high concentrations, tetrasodium pyrophosphate can actually react with the calcium in your teeth and bones, weakening them over time. I'm gonna give Arm & Hammer the benefit of the doubt here, and assume they don't put teeth-destroying amounts of this chemical in their product, but in doing a little environmental research I stumbled upon a more realistic issue with this chemical. It contains phosphates, which are common in many household products. They're not harmful to people, but when all of these phosphates get released into bodies of water, algae can feed off of them, and something called an algae bloom (basically an unregulated reproduction of algae) can happen, damaging the other organisms fighting for resources and space in the ecosystem.

Ducks struggling in the midst of a phosphate-induced algae bloom

Lastly let's take a look at a chemical that's found in most toothpastes - Sodium Fluoride. Sodium Fluoride leads to the production of Fluoropatite, which is a mineral found in tooth enamel. Basically, the Sodium Fluoride causes tooth enamel to be rebuilt, helping keep your teeth protected. Sodium Fluoride is toxic to humans at a fairly low dosage (5-10 g), but toothpaste has such a minuscule amount of Sodium Fluoride that this is extremely rare. There have been three documented cases of people eating so much toothpaste that they suffer from Sodium Fluoride poisoning. In high enough concentrations, Fluoride ions can cause serious problems for marine life, because it inhibits enzyme activity.

Experiment and Results

For my experiment, I designed a titration to test Arm & Hammer's claim of being able to "neutralize acids." I chose to compare it to two brands that also advertised themselves as "whitening" toothpastes - Crest (the cheapest one available) and Tom's (an "all natural" option).

Procedure

1.)  Prepare a solution of toothpaste/water (1 g toothpaste and 100 mL water)

2.) Add some indicator (bromothymol blue) to the solution

3.)  Slowly add Hydrochloric Acid to the solution until the color changes to yellow. This lets us know the solution is fully acidic.

4.) Record the amount of HCl that could be neutralized and compare the data to see if Arm and Hammer is significantly better at neutralizing acid than its competitors

Results

Just by looking at the color that each toothpaste solution appeared in the bromothymol blue indicator, it was clear that Arm & Hammer was the most basic.

From the titration results it became even more apparent that Arm & Hammer was by far the best acid neutralizer.

	Arm & Hammer	Tom’s	Crest
Amount of HCl needed to neutralize (mL)	18 mL	6 mL	1.5 mL

These results can largely be justified by the fact that one of Arm & Hammer's top ingredients is Sodium bicarbonate, which is responsible for its acid-neutralizing power. For Crest, their website lists Sodium Hydroxide (yes, the same thing that can burn your skin) as a "pH adjuster," but as my experimental results showed, this must be a very small amount of Sodium Hydroxide. Tom's uses Phosphoric Acid as its "pH adjuster," which is baffling because why would they want their toothpaste to be more acidic?

In conclusion, I'm fairly happy with the results of my experiment, as Arm & Hammer performed significantly better than its competitors when it comes to neutralizing acid. My chemical research was not quite as satisfying, and I would definitely suggest that Arm & Hammer replace the tetrasodium pyrophosphate with a phosphate-free tartar control ingredient.