Avoid fizzy drinks

Carbonated drinks (including the diet variety and sparkling water) can cause your teeth to look older than they really are. "These drinks are so highly acidic that they can actually dissolve the upper layers of the tooth," warns cosmetic dentist Dr Oliver Harman. They contain high amounts of phosphorus - a mineral that can leach calcium from your bones if you consume too much - and some scientists believe they can weaken your jawbone, increasing the chance of losing teeth.

According to Ken Wical, a professor of restorative dentistry at Loma Linda University in California, "Some researchers believe calcium is first robbed not from your hips or spine but from your jaw, leading to tooth loss. We see a number of young people who have the jaws of much older people, because of poor dietary habits such as drinking soda, along with not getting enough calcium."

Chew your food

Foods that work on the teeth like detergents are foods that require chewing. Apples, celery and carrots clean teeth naturally and foods such as spinach, lettuce and broccoli prevent staining by creating a film on the teeth that acts like a barrier. Major stainers will take their toll on your smile sooner or later, so steer clear of tea, coffee, red wine, curries and highly pigmented foods such as cherries and blueberries - anything, in fact, that will stain a white shirt.

Don't take drugs

Ecstasy causes jaw-clenching in users. A study conducted in 1999 by the University of Liverpool School of Dentistry found that 60% of ecstasy users examined had worn their teeth through the enamel and into the underlying dentine, compared with only 11% of non-users. As for cocaine rubbed on gums, Harman warns that it restricts blood flow, traumatises the tissue and inhibits nutrition of the gums. "Remember, gums keep teeth in place," he says.

Quit smoking

Smoking causes staining of the teeth and bad breath, and increases the risk of oral cancer and gum disease as it constricts blood flow to the gums. In fact, some gum specialists feel it's not worth providing advanced treatment for gum disease in smokers as there is very little chance of improvement. Smoking one pack a day for 10 years can cause a 10% loss of bone support. Long-term studies reveal that most tooth loss in 19- to 40-year-olds is associated with smoking more than 15 cigarettes a day. On a positive note, however, a study published in the Journal of Periodontology revealed that 11 years after quitting, former smokers' likelihood of having periodontal disease was not significantly different from that of those who had never smoked.

Relax

Bruxism is the technical name for tooth grinding and, according to the British Dental Health Foundation, it affects around one in 10 of us. It is often caused by stress and anxiety, and over a period of time can result in tooth damage and receding gums. The teeth may be pushed out of line and your bite may need adjustment.

To make matters worse, grinding usually occurs at night, with many of us unaware we are doing it. The following are signs that you may be suffering from bruxism: mouth, jaw and facial pain; limited jaw movement; sore gums and worn teeth. If you have a partner, ask them to listen for grinding sounds you may make while sleeping. The British Dental Association advises trying relaxation techniques before you hit the pillow and if you suffer from prolonged tooth grinding, talk to your dentist about options such as a special mouthguard to wear while you sleep.

Beware of bleaching

"A professionally applied whitening system will not damage teeth," says Dr David Bloom, a member of the British Academy of Cosmetic Dentistry. "But some over-the-counter bleaches are acidic, so can cause surface loss and sensitivity."

Stop biting your nails

Habitual nail chewers damage more than their cuticles; they can damage their teeth, too. "If you have weakened enamel, you end up with an exposed, dented, soft area in the centre of the tooth," Harman says, "and that's when a problem occurs. The denting is much softer than the enamel and if exposed to bad habits such as chewing nails, opening beer bottles or tearing off Sellotape, it will wear down." Often the middle part dissolves quicker than the outside and the brittle enamel is very prone to chipping, making the teeth look uneven and unattractive.