Diet soda can have the same effect on your tooth enamel as methamphetamine or crack cocaine use — and it’s not pretty.

In a three-person case study published in the March/April 2013 issue of the journal General Dentistry, Dr. Mohamed Bassiouny studied the teeth of a diet soda drinker and two drug addicts and found similar dental erosion among all three.

“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,” Bassiouny, a professor of restorative dentistry at Temple University’s Kornberg School of Dentistry, told HealthDay.

The three participants included a woman in her thirties who drank two liters of diet soda daily for three to five years, a 29-year-old methamphetamine addict and a 51-year-old habitual crack cocaine addict, according to the case study. All three came from similar socioeconomic backgrounds and lived in urban areas with fluoridated public water.

According to an Academy of General Dentistry press release, the three people experienced severe erosion of their tooth enamel, a condition caused by acid. When the enamel is worn away, teeth become more susceptible to cavities and other problems. Diet soda, methamphetamine and crack cocaine are all highly acidic substances, the release notes.

The American Beverage Association disputed the study’s claims, telling HealthDay in a statement that “the body of available science does not support that beverages are a unique factor in causing tooth decay or erosion,” and to imply that diet soda consumption caused the woman’s tooth erosion “is irresponsible.”

However, in an interview with Business Insider, Bassiouny defended his comparison, adding that over a long dental career he had observed hundreds of similar soda-caused erosion cases.

“I was trying to make a parallel between drug abusers — and the usual neglect for themselves — and put this with the same traits of someone who drinks diet soda,” Bassiouny said.

The idea that drinking diet soda might be bad for your teeth is not new, however, as evidenced by a 2011 Huffington Post blog written by New York City cosmetic dentist Dr. Thomas P. Connelly:

The problems with soda are twofold: first, the sugar content is bad for your teeth (but that fact is pretty obvious). The second bad part is the acidity, which is quite high in soda pop. Acidic content (aka pH) is measured on a scale of 0 (most acidic) to 14 (least). Battery acid is a 1 on the scale — tap water is a 7 (this may seem backwards, but yes, the higher numbers are less acidic. Blame science.)