"You look at it side-to-side with 'meth mouth' or 'coke mouth,' it is startling to see the intensity and extent of damage more or less the same," said Dr. Mohamed Bassiouny, a professor of restorative dentistry at the Temple University School of Dentistry in Philadelphia.
Methamphetamine, crack cocaine and soda - sweetened or not - are all highly acidic and can cause similar dental problems, Bassiouny said in a study published recently in the journal General Dentistry.
The acid in soda is in the form of citric acid and phosphoric acid, Bassiouny said. Without good dental hygiene, constant exposure can cause erosion and significant oral damage, he said.
Soda vs. drugs
In his study, he found that a woman in her 30s who drank two liters of diet soda daily for three to five years experienced tooth rot and decay remarkably similar to that suffered by a 29-year-old methamphetamine addict and a 51-year-old habitual crack cocaine user.
The younger man had used methamphetamine for three years, and often downed two or three cans of regular soda a day because the drugs made his mouth so dry. The older man reported an 18-year history of crack abuse.
The woman said concerns about weight gain led her to choose diet soda over regular, and admitted that she had not seen a dentist in many years, according to the study. She also associated sweetened beverages with a higher risk of tooth decay.
Her teeth were soft and discolored, with many destroyed by erosion. She usually sipped the beverage directly from a can or a bottle, and held the soda in her mouth before swallowing, Bassiouny said.
"She also mentioned that when doing so, she habitually leaned on her left side against the arm of the sofa while watching television," he said. The "massive" damage to the left side of her mouth bore this out and resulted in what is called a collapsed bite.
"None of the teeth affected by erosion were salvageable," Bassiouny said. The woman had to have all of her teeth removed and replaced with dentures.
Methamphetamine and crack are known to ravage the mouths of users, and the two drug abusers needed all of their teeth extracted.
Besides exposing teeth to damaging acid, these illegal drugs reduce the amount of saliva in the mouth, providing less opportunity for the acids to wash away. The drugs also cause systemic health problems that affect dental hygiene. Previous studies have linked "meth mouth" with rampant decay.
Soft-drink manufacturers fight back
A group representing soft drink manufacturers said this case study should not be seen as an indictment of diet sodas generally.
"The woman referenced in this article did not receive dental health services for more than 20 years - two-thirds of her life," the American Beverage Association said in a statement. "To single out diet soda consumption as the unique factor in her tooth decay and erosion - and to compare it to that from illicit drug use - is irresponsible.
"The body of available science does not support that beverages are a unique factor in causing tooth decay or erosion," the group said. "However, we do know that brushing and flossing our teeth, along with making regular visits to the dentist, play a very important role in preventing them."
Dr. Eugene Antenucci, spokesman for the Academy of General Dentistry, said he was not surprised by Bassiouny's findings.
"From my experience, the damage that happens to people's mouths from cocaine or methamphetamine are degrees greater than what I see from soda, but I see a lot of damage from soda," said Antenucci, a dentist in Huntington, NY.
Damage from excessive soda consumption can cause "very deep brown stains, where it's actually eroded into the tooth, and the teeth are soft and leathery," he said.
Prevention is the best cure, Bassiouny said. How often you drink soda, how much you drink and how long it's in your mouth all are important factors. "You can help prevent it from happening by reducing any of those," he said.
Sugar-free soda is no better than regular soda when it comes to dental decay, Bassiouny added. "Both of them have the same drastic effect if they are consumed in the same frequency, the same amount and the same duration," he said.
Antenucci said people need to keep in mind that they are drinking something that is highly acidic when they pick up a soda.
"Knowing that, you limit it and understand that you need to clean your mouth afterward," he said. "Even simple water will wash away the acidity. And everyone should brush twice a day, if not more often."
Should people give up drinking soda? "You'd be better off if you didn't drink the soda," Antenucci said, "but in my mind there's not a reason for that extreme."
The Academy of General Dentistry has tips on healthy eating for healthy teeth.