Pictures are always a far better way to demonstrate something like this. This is known as “Meth Mouth” and it’s a pretty good reason to not become a methamphetamine user.
Now, according to the American Dental Association, “The rampant caries associated with methamphetamine use is probably caused by a combination of drug-induced psychological and physiological changes resulting in xerostomia (dry mouth), extended periods of poor oral hygiene, frequent consumption of high calorie, carbonated beverages and tooth grinding and clenching. Some reports have also speculated that the acidic nature of the drug is a contributing factor.”
Though, hopefully we convinced you that meth wasn’t a great idea before you even read that.