Given all the chewing, crunching, biting, and gnashing they do, our teeth are surprisingly resilient. Still, everyday wear and tear and the natural aging process take a toll.

Here's what happens to teeth as we age -- and what you can do to keep your teeth strong and sparkling for a lifetime.

Preventing Acid Erosion

By far the biggest threat to teeth is sugary and starchy food. These carbohydrates ferment, causing the bacteria in the mouth to produce acids. Those acids can quickly eat away at the enamel of teeth. As a result, this creates tiny pits where tooth decay can form.

Most of us assume that sugary candy is the worst offender. But sweetened carbonated beverages, such as colas, can be even more dangerous, since carbonation increases acid levels in the mouth. Some recent studies have singled out sports drinks as a particular threat to tooth enamel.

What to do:

• Go easy on sugary foods, especially carbonated soft drinks and sports drinks.
• Avoid frequent snacking, which causes acid levels in the mouth to remain high over an extended time.
• If you get a craving for something sweet, chew sugarless gum. Chewing increases saliva production, which helps cleanse the mouth and neutralize acidity.
• Brush your teeth at least twice a day for two minutes and floss daily. Daily dental hygiene reduces bacteria levels in your mouth.
• See your dentist every six months for a regular checkup that includes removing plaque buildup.

Preventing Mechanical Wear and Tear on Your Teeth

The function of teeth is mostly mechanical -- to mash and grind and otherwise break up food to make it more easily digested. For the most part, our teeth are resistant to cracks and chips.

"Contrary to what many people assume, teeth do not become more brittle with age," says Steven E. Schonfeld, a private practice dentist and spokesperson for the American Dental Association. "Still, we see patients all the time who have cracked or chipped a tooth biting down hard on something like an olive that still has a pit or a kernel of unpopped popcorn."

Teeth that have fillings or root canals are particularly vulnerable, since they don't have the strength of structurally intact teeth.

Another problem that causes wear and tear is the habit of grinding or clenching teeth. Called bruxism, it is frequently caused by stress or anxiety. Over time, bruxism can wear down the biting surfaces of teeth, making them more susceptible to decay.

What to do:

• Avoid chewing ice and other very hard foods.
• Double-check to make sure that pitted foods have no pits before you bite down on them.
• See your dentist regularly. He or she can spot cracked or broken fillings that may weaken teeth. Your dentist will also check for signs of bruxism. In many cases, people who grind or clench their teeth aren't aware of the habit or the damage they are doing to their teeth. If you show signs of bruxism, your dentist may recommend a mouth guard that can be worn at night to prevent grinding.

Preventing Stains on Your Teeth

Certain foods -- especially coffee, tea, and red wine -- can stain teeth. Tobacco, both smoked and chewed, also discolors teeth. For the most part, stains are a cosmetic issue. "But stains typically form where there is organic build-up, or plaque, on teeth, so it's important to have them removed as part of a regular checkup," says Iacopino.

What to do:

• Avoid foods that stain teeth.
• Brush regularly to remove plaque buildup, which will help your teeth resist stains.
• Have your teeth cleaned professionally every six months. Your dentist or dental hygienist can remove plaque and tartar that a toothbrush can't reach.

If you still aren't satisfied with the color of your teeth, talk to your dentist. Toothpastes and bleaching systems can whiten teeth, and home bleaching kits are also available. Be sure to follow the directions for use. Overused, the chemicals can irritate gum tissue. Overuse can also lead to teeth that are unnaturally white.

Preventing Gum Problems

By far the biggest threat to healthy teeth is gum disease. The risk of gum problems increases with age, especially as pockets form at the gum line where bacteria can grow. Left untreated, bacterial infections can cause inflammation that damages connective tissue and even bone, leading to tooth loss.

What to do:

• Brush and floss regularly to remove bacteria.
• For added protection, use an antibacterial mouthwash.
• Go to your dentist for a regular checkup every six months. This is particularly important for detecting gum disease early. "Although there are symptoms of gum disease that can serve as early warning signs, by the time they appear it's often too late to reverse the disease process," says Sam Low, DDS, president of the American Academy of Periodontology.
• Since gum disease is an inflammatory process, eating foods that suppress inflammation may help. Growing evidence suggests that a diet rich in omega-3 fatty acids can help dampen inflammation, says Iacopino. Good sources of omega-3 fatty acids include fish, fish oil, and flaxseed.

Preventing Dry Mouth as You Age

Called xerostomia, dry mouth can drastically increase the risk of decay and gum problems. A healthy flow of saliva helps clean teeth and neutralize acids that otherwise eat away at the tooth enamel.

"Saliva flow doesn't necessarily decrease with age. But as many as 800 different drugs cause dry mouth as a side effect," says Iacopino. "Many of these are medications people take as they get older."

What to do:

• A drop-off in saliva levels can very quickly cause problems. So at the first sign of dry mouth, talk to your doctor.
• A change in prescriptions may help alleviate the problem. If not, your doctor may recommend chewing sugar-free gum. Gum increases saliva flow.
• Saliva-like oral mouthwashes are also available.