Testing at-home teeth-whitening products.

Tooth whiteners are primed to be the next deodorant: a once-optional form of personal hygiene that's now simply an obligation. It's only a matter of time because the more of us who get whitened, the grungier your unwhitened teeth will appear in contrast. Man, look at those choppers! Nasty! Aren't you going to do something about that? There has lately been a boom in tooth-whitening techniques, both at home and in the dentist's office. I asked St. Louis-area dentist (and frequent Slate dental correspondent) Dr. William Hartel about the various options, then tried a few for myself. Below, my findings.

At the Dentist's Office

Dentists have been whitening teeth for years. You have two options here: 1) The dentist gives you special equipment, and you do it yourself at home, over a few weeks; or 2) the dentist does it entirely at his office, in a single day.

With Option 1, the dentist molds vinyl trays to fit your teeth. Then he gives you a prescribed gel to put in the trays. This gel will contain carbomide peroxide (which reacts with your saliva to become hydrogen peroxide) at a concentration somewhere between 10 percent and 25 percent. You go home, load the gel into the trays, wear the trays two to four hours per day for two to three weeks, and your teeth get whiter as the gel oxidizes their stains. This option has been available for more than a decade, and it works. You'll see a difference within two days. The whole thing costs about $200 to $400, and the effects won't wear off for several years.

Option 2 is actually the same thing but massively speeded up. The dentist puts the peroxide on your teeth and then uses a laser (or plasma arc lamp) to activate the oxidization and whiten your teeth much more quickly. You spend about an hour in the chair, and it costs between $400 and $1,000 (one Slatester paid $800 for this service). The results are the same as with Option 1, but it's clearly more convenient. Of course, it's more expensive, too, and you spend a full hour in the dentist's chair with your mouth open the entire time—which can be quite unpleasant.

At Home

First of all, let's crush the myth of "whitening toothpaste" for good. I've said it before; I'll say it again: Whitening toothpastes don't work. They don't do anything regular toothpastes can't do. They just cost a whole lot more (up to $7 for a tube of Rembrandt).

Toothpaste—any toothpaste—removes only surface stains. That yellowness that's bothering you is likely not on your surface enamel (which is transparent and can be polished with toothpaste), but rather in the dentin inside your teeth (where toothpaste can't reach). Your dentin gets yellower as you get older, even if you don't smoke tobacco or drink coffee. It's the yellow within this dentin that hydrogen peroxide can bleach away—when applied correctly and for an extended period.

So, can you whiten your teeth at home? Yes, but you need a hydrogen peroxide kit that mimics what the dentist does. I tried three such kits, then ranked them from worst to first.

Absolute worst: Natural White Pro Tooth Bleaching System.
I at first thought this would be the best product. It came in a fancy box with plastic dental trays, "pre-whitening toothpaste," an "oral rinse neutralizer," and a complicated set of steps to follow. But I soon realized this was all nonsense. The "oral rinse neutralizer" is plain old mouthwash; the "pre-whitening toothpaste" is just toothpaste. My dental expert calls this "mad scientist marketing," wherein they convince you you're accomplishing something by assigning lots of technical-seeming busy work. Really, all you need (or want) is the dental trays and the peroxide whitening gel.