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Soft drinks are hard on the teeth

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The square off: Six solutions--five soft drinks and a 99-cent drain cleaner--loom large over their potential victims in the race to decay (Howard Swains/CNS)

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The six teeth--otherwise to be discarded from a dental office in Harlem, N.Y.--await their sugary fates (Howard Swains/CNS)

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The teeth are finally submerged in their corrosive baths. From left to right: Nesquik, Snapple, drain cleaner (Howard Swains/CNS)

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After two weeks, mold had developed on the top of the Nesquik, orange juice and iced tea samples. The teeth submerged in the solutions did not look much more healthy. Clockwise, from back left: drain cleaner, orange juice, Nesquik, Gatorade, Snapple, Coca-Cola (Howard Swains/CNS)

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Their punishment over, the teeth pose for the end of experiment photograph. Clockwise, from back left: Tropicana orange juice, chocolate Nesquik, drain cleaner, Gatorade fruit punch, Snapple iced tea, Coca-Cola. Note the tooth left in drain cleaner has split into two parts (Howard Swains/CNS)

It was a simple idea. Take five teeth, five soft drinks, four weeks and one hypothesis borrowed from junior high science class: A tooth left in a cup of sweet liquid will quickly decay into a gruesome lump.

But does the hypothesis measure up to reality? Are the sodas we drink actually that corrosive to our teeth? And if so, which are the worst offenders?

The plan was to create a kind of race. A dental office in Manhattan's Harlem kindly donated some undecayed, extracted gnashers that otherwise would have been discarded. Five teeth were each placed in a variety of sugary baths. While their progress into decay was charted and photographed, experts were consulted to describe exactly what was going on.

"It doesn't duplicate life exactly," said Dr. Matthew Messina, a spokesman for the American Dental Association. "But it shows how the enamel is definitely dissolving off the teeth."

The challengers in the contest were the kind of drinks much loved by children and adults: Coca-Cola, Snapple (lemonade flavor), Gatorade (fruit punch variety), Nesquik (chocolate) and Tropicana juice (orange and mandarin). For contrast, a sixth tooth was placed in a glass of 99-cent drain cleaner. The theory: Perhaps we'd be better off drinking that solution than cleaning our drains with soda.

The teeth and the liquids were arranged in plastic champagne glasses to add a sense of occasion to the experiment. Then they were left alone, and the research began.

In recent years, sodas have been regularly cited as contributing to the increase in obesity and diabetes. In March, in a bid to address some of the criticisms, Coca-Cola and Pepsi announced details of a plan to market drinks fortified with vitamins and minerals. But the new measures do not address sodas' longstanding link to tooth decay.

In 2004, for instance, researchers at the University of Maryland Dental School divided common drinks into three categories--cola beverages, non-cola beverages and teas and coffees--and submerged teeth for 14 days in samples from each group.

The teeth were weighed at regular intervals to determine how much of their enamel was dissolving. The study found that the vast majority of soft drinks "exhibited a progressive attack" on teeth.

While canned iced tea dissolved enamel 30 times more than brewed tea, other drink groups were even worse. Cola drinks dissolved enamel 55 to 65 times more than water; the non-colas dissolved 90 to 180 times more enamel than water.

A precision scale was not available for the less scientific apartment-based project of 2007. But visual examination determined that it took about a week before any of the teeth began to show the ill effects of their submersion.

At seven days, the tooth bathing in Gatorade had become entirely stained by the blood-red color of fruit punch, while the teeth in Snapple and Coke were gradually turning brown. A thin layer of mold had developed on top of the Nesquik sample, trapping the tooth in a sort of chocolate mousse.

In the orange juice, mushy gray moldlike matter had attached itself to the tooth. Things looked much more appealing in the drain cleaner sample: The liquid had bleached its subject pearly white.

According to the Maryland study, two weeks of total immersion in a soft drink is the equivalent of about 13 years of actual soda drinking. These kinds of experiments show "what in reality is the cumulative effect of a lifetime of erosion," said Dr. Kenton Ross, a dentist in Fayetteville, Ark., and spokesman and fellow of the Academy of General Dentistry. Ross was not involved in the Maryland study, but through his own research he has concluded that "drinking any type of soft drink poses a risk to the health of your teeth."

In basic terms, soft drinks contain differing levels of sugar and acids--sometimes as much as 12 teaspoons of sugar in a 12-ounce serving, according to Ross. Naturally occurring bacteria that live in the mouth feed on the sugar and produce a different acid that attacks the teeth and erodes enamel.

Saliva provides a natural defense mechanism, and regular tooth brushing also helps remove the damaging acids. But typical soft drink consumption--sipping from increasingly enormous containers over a long period of time--gives teeth a constantly fresh coating of the harmful solution.

"Parents and kids need to understand the mechanics of how cavities occur, and how what they do can make them worse," said Messina, who has a dental office in Cleveland. "And one of the worst things we can do is take a very sugary, acidic drink and sip it all day."

For this reason, dentists advise consuming sweet beverages in moderation, finishing them quickly and drinking through a straw, which takes the liquid to the back of the mouth.

They also advise frequent professional cleanings and regular brushing, especially at night.

“We don’t need to stop drinking soft drinks,” Messina said. “We just need to understand what’s going on and take the appropriate preventative steps to reduce the problem.”

Running a race-to-decay experiment can add a stark visual incentive to adhere to the advice of dentists--and parents.

The teeth in the experiment took on a horror-movie appearance that became progressively more disgusting. After four weeks, the tooth bathing in Coca-Cola was brown and sticky and resembled a chewed-up piece of candy. The orange juice and iced tea had corroded their subjects and turned them yellowy brown with suspicious specks of a darker hue. The Gatorade bather was still bright scarlet, while the Nesquik had solidified around its tooth, suspending it in brownish-green sludge with lumps of sinister matter stuck to the subject.

Surprisingly, perhaps, only one of the teeth had markedly changed in shape: The tooth in drain cleaner was still very clean, but, alas, it had also broken in two.

All such outcomes are worth remembering the next time you reach for something sweet to drink--or to clean your drains.

E-mail: has2114@columbia.edu