[Narrator] If your smile's a bit lackluster,

you could go to the dentist

for a potent blast of tooth-whitening.

But whitening strips put the same ingredients

in a package for home.

What's inside these special strips?

Hydrogen peroxide is the star of the show.

It's the same stuff you bleach your floors with,

but at a much lower concentration.

It breaks apart into radicals,

molecules with reactive, unpaired electrons.

Those guys like to attack stain molecules

and break them apart.

Hydrogen peroxide is an acid,

which is why you need sodium hydroxide,

a base, along with it.

It makes the strip less acidic,

so it's easier to keep in your mouth.

Sodium saccharin helps balance out the bleach, too.

It cloaks the bitterness without cavity-causing sugar.

Then there's the delivery system.

It starts with PEG, or polyethylene glycol.

These chains of carbons and oxygens

love binding to the water in your saliva,

creating a layer of sticky gel.

They also link up at the ends

to other absorbent polymers, including acrylates copolymer.

It's the same stuff that mops up liquid

in disposable diapers.

It takes up so much water that it might dehydrate teeth,

which could be why they're sometimes

sensitive after whitening.

Ouch.

For an extra benefit,

some formulas include sodium acid pyrophosphate,

an anti-tartar agent.

It puts a cap on calcium ions, preventing tartar crystals

from building on top of them.

Now go show off your pearly whites.

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