A smile is more than just contagious. It can also give away your age.

“Just as white, straight teeth convey youth, a smile with crooked, discolored, worn, or missing teeth is associated with an aged look,” Edmond Hewlett, DDS, professor of restorative dentistry at UCLA's School of Dentistry tells WebMD.com. “The adage ‘long in the tooth,’ used to describe older persons, reflects the fact that gum disease causes gums to recede and teeth to appear longer as a result."

To keep your mouth looking younger, follow basic this basic oral hygiene routine twice a day every day: floss and brush. And every six months, see a dentist.

While most people brush, not everybody takes the time to floss, which makes a difference.

“They take their looks seriously and the smile is a priority, but people don’t think about their gums. Brushing takes time, and flossing is one of the most difficult habits. Only 25% of people floss and I don’t think people see the benefits," says Samuel Low, DDS, MS, president of the American Academy of Periodontology and professor emeritus of periodontology at the University of Florida, who estimates that it takes two to three minutes per day to floss properly, but "these days, people are crunched for time.”

In addition to good oral care, there are a few other things you can do as well.

Stained teeth are a dead giveaway of age. Yellowed or discolored teeth ruin a smile, no matter how genuine. Smoking and drinking are the major culprits of yellowed teeth. Give up smoking and switch your red wine for white and coffee for green tea, which is a natural teeth whitener and has a lower level of caffeine. Avoiding foods and beverages that stain teeth, coupled with brushing and flossing can limit new stains.

For already stained and discolored teeth, there are various whitening options. Although brushing and flossing are the best ways to enjoy a younger smile, the drugstore offers a variety of teeth whitening products from toothpaste and mouthwash to dental strips that temporarily remove stains and whiten teeth. For a longer-lasting (and more expensive) white smile, visit the dentist. Most dentist offices now provide laser-teeth whitening procedures as well as less expensive, whitening options like dental trays that use bleaching gels. Teeth whitening mechanisms give a whiter smile, but they may also cause sensitivity in many patients.

Dental veneers may also provide a fresh set of teeth, but they can also look like false teeth if they are too white or too large—making a smile older rather than younger.