6 Things Your Dentist NEVER Puts in His Mouth

Other people’s toothbrushes

Whether it’s your significant other’s or your best friend’s toothbrush and you forgot yours for a night away or a vacation, resist the temptation to borrow a toothbrush. “Not only are they full of bacteria, but the biggest risk is that, if the person is sick or about to get sick, you will too,” warns Dr. Dorfman. “There are also studies that suggest that the bacteria that cause tooth decay can be spread through sharing toothbrushes.”

Nails

On the scale of self-harming nervous habits, biting your nails might not be the worst. But Lana Rozenberg, DDS, New York City-based dentist, warns that the habit can flatten the edges of your front teeth. “Over time, your teeth can wear faster and nail-biting can create cracks on the enamel of your teeth until they become hypersensitive,” she says.

“The biting action also puts your jaw in an unnatural position that can stress your joints, can cause grinding and clenching—and this prolonged pressure and friction can cause pain in your teeth, ears, and jaw.”