When you look in the mirror, you may notice that your teeth have a slight yellow hue. While teeth whitening treatments can restore the whiteness of your smile, the discolouration is likely to return if you don't address the underlying cause. Learn about the top five causes of yellow teeth to find out how to can keep your newly whitened smile as bright as possible.

1. Smoking

A smile that looks more yellow than white is one of the characteristic side effects of smoking. Cigarette smoke contains chemicals that cling to the surfaces of your teeth and make them appear yellow, even if you brush them every day. If you want your teeth to stay white after a professional teeth whitening treatment, you will need to kick the habit.

2. Red Wine

Red wine has many reported health benefits, but unfortunately it's not good for the colour of your teeth. Red wine contains high levels of polyphenols, which are naturally occurring chemicals that give fruits and vegetables their colour. These polyphenols can stain teeth. Try switching from red wine to white wine, which has less staining potential. When you do indulge in red wine, rinse your mouth with water after every glass to wash the staining red liquid away from your teeth.

3. Coffee

Coffee is one of the biggest causes of stained teeth, particularly now that there is a coffee shop on almost every street corner. If you can't give up your morning caffeine hit, try adding milk to your coffee instead of drinking it black to reduce the likelihood of stains developing.

4. Black Tea

Like coffee, tea contains tannins, compounds that may have health benefits but also increase the risk of a stained smile. Black tea contains the highest levels of tannins. Try drinking other types of tea, such as green tea, white tea or herbal tea, to help keep your teeth white.

5. Enamel Damage

Some yellow teeth are not stained; instead, the enamel coating that covers them is so thin that the naturally yellow inner part of the tooth, also known as the dentin, shows through. If whitening products and treatments don't help to whiten your teeth, see your dentist to check for signs of enamel damage. Your dentist may be able to recommend an enamel-strengthening toothpaste or other type of treatment to strengthen your tooth enamel. Thin enamel can lead to tooth sensitivity or an increased risk of decay, so it's important to address this problem as soon as possible.