Oct 15, 2014 06:29 AM EDT By Staff Reporter, UniversityHerald Reporter

University of Iowa researchers have debunked the myth that strawberry-baking soda recipe can help restore the pearly white colour of teeth.

The researchers said that strawberry and baking soda formula just removes superficial debris, but does not make them any whiter. The other methods (over-the-counter products, professional whitening, and prescribed whitening products), however, not only remove the leftovers from the mouth, but also provide a deeper, and longer-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 associate professor and author So Ran Kwon, in a statement. "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."

For the study, the researchers rubbed organic strawberries and baking soda on 20 recently-extracted teeth for five minutes. The teeth were then subjected to gentle brushing. The procedure was carried out for 10 consecutive days, similar to those prescribed by pro-all-natural teeth-whitening experts.

Based on color-measurement tests and evaluations with a spectrophotometer, the researchers found that the teeth brushed with the strawberry-baking soda mixture showed no evidence of whitening.

The researchers also exposed three other groups of 20 extracted teeth to teeth-whitening procedures like teeth whitening at a dentist, tooth-whitening regimen and whitening strips. All these procedures showed visible whitening in the tests.

According to the American Dental Association, strawberries are not effective as teeth whiteners because they lack hydrogen peroxide and carbamide peroxide, which are the key ingredients in tooth-whitening products. Apples and lemons, also popularly advertised as tooth whiteners, have no hydrogen peroxide and carbamide peroxide.

Kwon said that the strawberry-baking soda mix, in fact, reduces the surface hardness of teeth, known as microhardness, by up to 10 percent, due to the erosive effect of citric acid in the fruit.

"These acids are not whitening agents and that explains why we have those results," Kwon said.

The finding is published in the journal Operative Dentistry.                    

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