Everybody knows that methamphetamine (meth, crank, crystal and speed) is a dangerous and powerfully addictive drug. Less well-known, however, is the terrible effect it can have on the teeth and mouth.

More than 12 million Americans have tried methamphetamine, which can be swallowed, injected, snorted or smoked, according to the 2004 National Survey on Drug Use and Health. The majority of users range between 18 and 34 years of age.

"Meth" users can go from having healthy teeth to extremely sensitive teeth to missing teeth in about a year. This condition is often called "meth mouth."

"Meth mouth robs people, especially young people, of their teeth and frequently leads to full-mouth extractions and a lifetime of wearing dentures, says Robert M. Brandjord, president of the American Dental Association. "Meth mouth is characterized by rampant tooth decay and teeth described by meth users as blackened, stained, rotting, crumbling or falling apart."

Dr. Brandjord explains, "The extensive tooth decay of meth mouth is attributed to the drug's dry-mouth effect and its propensity to cause cravings for high-calorie carbonated beverages, tooth grinding and clenching, and extended periods of poor oral hygiene."

In an effort to highlight this condition, the ADA has posted educational materials on its Web site www.ada.org for dentists and their patients.