Last week, while appearing on The Ellen DeGeneres Show, the singer revealed that she brushes her teeth only about three times a week.
"My teeth are so white and I don't like them to feel too slippery, but I do use Listerine and I do floss everyday," she told DeGeneres. "But I don’t brush them everyday. I’ll use a shirt or something ... I know it's gross, but I always have fresh breath."
Simpson’s dentist, Dr. Bill Dorfman, who appeared on an episode of Simpson’s previous reality show Newlyweds: Nick and Jessica and maintains a practice in Los Angeles, says he's surprised and concerned about her brushing habits.
"I was kind of shocked. I assumed everybody brushed their teeth all the time," he tells PEOPLE. "People pay us a lot of money for that slippery feeling. It’s kind of the best part."
But this wasn't the first time Simpson has talked about her lack of brushing. In March, the singer told a group of people a similar story at the "iheartradio presents an Evening with Jessica Simpson" in New York.
"Find me when I'm 60 and [my teeth] will probably be all out, but I literally have these strong powerful teeth that don’t need to be brushed," Simpson told the audience.
Dorfman says people should be brushing and flossing after every meal, or it can cause anything from inflamed gums to heart disease.
"It's great that she’s flossing all the time, but you have to brush too," Dorfman recommends. "What goes on in your mouth really affects your whole body."