Drinking large quantities of carbonated soda can be as damaging to teeth as methamphetamine or crack cocaine, U.S. scientists say.

A case study published in General Dentistry found the consumption of illegal drugs and abusive intake of soda could cause similar damage to the mouth through the process of tooth erosion.

Lead author Mohamed A. Bassiouny said tooth erosion occurs when acid wears away tooth enamel -- the glossy, protective outside layer. With compromised enamel, teeth are more susceptible to developing cavities, as well as becoming sensitive, cracked and discolored, Bassiouny said.

The case study compared the damage in three individuals' mouths -- an admitted user of methamphetamine, a previous longtime user of cocaine and an excessive diet soda drinker. The individual who drank soda consumed 2 liters, or 2.1 quarts, of diet soda daily for three to five years, Bassiouny said.

Each participant admitted to having poor oral hygiene and not visiting a dentist on a regular basis.

The study found the same type and severity of damage from tooth erosion in each participant's mouth.

"The striking similarities found in this study should be a wakeup call to consumers who think soda -- even diet soda -- is not harmful to their oral health," Bassiouny said.

--UNITED PRESS INTERNATIONAL