White Teeth, But at What Cost?

A recent study looks at the abundance of teeth-whitening gels, strips and paint-on films. Host Madeleine Brand speaks with Slate medical contributor Dr. Sydney Spiesel about how well they work and how safe they are.

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MADELEINE BRAND, host:

From NPR News it's DAY TO DAY.

Anyone can have a dazzling movie star smile - at least that's the promise of all those teeth whiteners at the drug store.

So how white can you make your teeth with all those gels and bleaches? And really, how safe are they? Our medical contributor, Dr. Sydney Spiesel, has been brushing up on the subject. He's a pediatrician and he writes a medical column for the online magazine Slate. And Syd, welcome back to DAY TO DAY.

Dr. SYDNEY SPIESEL (Pediatrician): Thank you, and always nice to be here.

BRAND: Now I understand you've reviewed a new study about tooth whiteners, and tell us about that study.

Dr. SPIESEL: Well it was comprehensive study done under the direction of Dr. Hana Hasson, who was a dentist at the University of Michigan. And she put together - she looked at about 400 papers in the literature of tooth whiteners. And she was kind of looking for things that were very specific. She wanted only products that could be used at home. She wanted products that - where you could - you had some basis of comparison: either the tooth-whitener was compared with another tooth-whitener, or was compared with placebo.

And she wanted studies where the measurement could be done objectively and over a two-week visit.

BRAND: So these aren't the laser tooth-whitening that you'd get in the doctors office, these are like the Crest Whitestrips or those gels that the doctor can give you.

Dr. SPIESEL: Yes, or that you can just walk in the drug store and buy yourself in the dental aisles these days. Some of these are gels, and some are paint-on films that dentist will paint on your teeth. And others are these whitening strips that you can apply to your teeth.

BRAND: And how well do they work?

Dr. SPIESEL: Well actually, surprisingly, they worked pretty well - at least in the short term. The gels work best, but they have the down side of having a little bit more irritation - your teeth become a little bit more sensitive. Your gums become a little bit irritated, sometimes, with the gels. But the gels work pretty well, the whitening strips work almost as well, and the paint-on films - not quite as well. But they are definitely using the objective measurements - either a colorimeter, an electronic machine that measures change in the color of your teeth, or some really darling little pseudo teeth that are made in a set of different colors that somebody can hold up next to your teeth to compare. There was no question that there was objective improvement by all of these products.

BRAND: And then, you know, you got to wonder - putting all these chemicals in your mouth and sometimes sleeping with them in your mouth - are they safe?

Dr. SPIESEL: All I can tell you is that in the short term they seem safe. Nobody has really looked at these things in a long term way. One of the things that I found interesting in reading these studies, is that the active materials - and there are only two active materials really that account for about virtually all of these products. One is hydrogen peroxide in different concentrations, and the other is some stuff called carbamide peroxide - both act by releasing oxygen, and the free oxygen is what really bleaches the teeth.

And what was interesting is, in the few studies that have been done where they look at it in a kind of critical way, it turned out that the active ingredients penetrated very, very quickly into the enamel, and through the enamel, and into the dentin, and actually into the pulp really within minutes of application.

As I say, we really don't know about any harms - any long term harms. There may be, there may not be.

BRAND: Would you use it?

Dr. SPIESEL: I haven't used it. Sometimes I go into the bathroom and smile at the mirror and I think, hmm - but then again, I'm very conservative guy - so probably not.

BRAND: That's opinion from Dr. Sydney Spiesel of the Yale Medical School. He's also a medical writer for the online magazine Slate. Thanks Syd.

Dr. SPIESEL: Thank you.

BRAND: More coming up on DAY TO DAY from NPR News.

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