After enduring a visit to the dentist to get a tooth pulled, you might wonder—as the novocaine starts to wear off—what happens to teeth after they’re extracted?

Although some dentists tell their patients that it’s against the rules for patients to take their pulled teeth home as a memento, the Centers for Disease Control and Prevention (CDC), American Dental Association, and Occupational Safety and Health Administration (OSHA) guidelines say otherwise. These organizations allow for dentists to return extracted teeth to their patients, if the patients request it. The only caveat is that the dental office should properly disinfect the teeth before handing them back to the patient.

If patients choose not to take their pulled teeth home with them, the teeth can go a variety of places. If dentists want to dispose of pulled teeth, they must throw them out in specially marked medical waste containers. Because pulled teeth may have tiny amounts of blood, saliva, or tissue residue on them, they are potentially infectious materials. Dental offices pay medical waste management companies to pick up the containers and incinerate the teeth along with other biomedical waste.

If the teeth have amalgam fillings, though, dentists need to send the teeth to a licensed recycling center that processes metals. Classified as hazardous waste, teeth with amalgam fillings cannot be incinerated because the heat could cause the mercury to be released into the air. (Mercury poisoning from inhaling mercury vapor is something you definitely want to avoid.) Metal recycling centers distill the mercury from the amalgam filling, and that mercury can then be used in products like laboratory thermometers, thermostats, and fluorescent light bulbs.

Besides being thrown out or recycled, extracted teeth can help educate the next generation of dentists. Dentists may donate extracted teeth to dental schools or bring the teeth with them to continuing education courses to practice dental techniques. Additionally, dental research companies use extracted teeth to discover new methods and better ways for dentists to treat teeth.

Dentists can even profit off the teeth they pull, if they sell them to scrap metal dealers. After extracting the gold from dental crowns, scrap metal companies will send a small check to the dentist for a percentage of the value of the gold. But as periodontist Lonnie S. Rattner told the Chicago Sun-Times in 1997, "Believe me, no dentist is paying his country club dues with the amount of gold he's saving over a year."