Fruit and Baking Soda Mix Does Not Whiten Teeth, Study

First Posted: Oct 15, 2014 05:13 AM EDT

A latest study knocks the popular belief that brushing teeth with fruit and baking soda helps whiten them.

The factors that contribute to the discoloration of teeth include smoking, medication, etc. But, there are certain fruits that have the ability to whiten teeth naturally. Previous studies have shown how tart fruits like strawberries can be useful in whitening teeth because it contains malic acid.

They believe mixing strawberries with some baking soda and applying the concoction on teeth helps whiten them.

But, researchers at the University of Iowa showed that this cheap and organic method is not very effective in whitening teeth.

Led by associate professor So Ran Kwon, the researchers found that strawberry and baking soda formula only eliminated some of the superficial debris. The other methods help get rid of the food and offer a lasting effect.

"The only benefit of the do-it-yourself method (strawberries and baking soda) is while it seems to make your teeth look whiter, they look whiter because you're just removing plaque accumulation on your teeth," said Kwon, sole author on the study. "You really want something that penetrates into your teeth and breaks down the stain molecules. If you don't have that, you get just the superficial, and not the whitening from the inside, which was what you really want."

In the experiments conducted by Kwon, the researchers rubbed a mixture of California-grown organic strawberries and baking soda on a set of 20 teeth that was recently extracted. The mixture was rubbed for five minutes, followed by gentle brushing. This procedure was repeated for three times over a period of 10 days.

They noticed that the teeth that were brushed with the strawberry-baking soda mixture exhibited no real whitening (based on two famous color-measurement tests and evaluation using a spectrophotometer).

Three other groups of 20 extracted teeth were again subjected to other whitening procedures, replicating the teeth whitening at dentists', a prescribed tooth-whitening regimen and whitening strips that are available at the medical counters. All showed noticeable whitening in the observational and instrumental tests.

According to the American Dental Association, it is the chemistry of strawberries due to which they fail to work as teeth whiteners. Though they may taste great, they basically lack hydrogen peroxide and carbamide peroxide - the two key ingredients that is present in tooth whitening products.

Apples and lemons are also referred to as tooth whiteners and they have no hydrogen peroxide and carbamide peroxide, indicating that their effectiveness as tooth whiteners is limited.

Another downside noted in the strawberry-baking soda mix is that they reduced the surface harness of the teeth called microhardness by almost 10 percent, due to the erosive effect of citric acid in the fruit.

"These acids are not whitening agents," said Kwon, currently in the UI College of Dentistry and Dental Clinics, who performed the experiments while at Loma Linda University in California, "and that explains why we have those results."

The study was documented in the journal Operative Dentistry.

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