Most of us drink at least two cups of chai a day, and our teeth show it. But not every dark tooth is a tea stain. Some discolouration sits on the surface and some is inside the tooth, and the difference decides what will actually work.
On the surface or inside?
Dentists split stains into two groups. Surface stains, the ones we call extrinsic, sit on the outside of the enamel and in the sticky film that builds up on teeth through the day. Deeper stains, called intrinsic, are inside the enamel or the dentine underneath. Plenty of people have a bit of both.
The usual suspects on the surface
Tea is the big one in India, especially strong tea without much milk. It's full of tannins, which cling to enamel. Coffee does the same. Cola, red wine, beetroot and berries add their share, and so do turmeric-heavy curries if you eat them every day.
Tobacco in any form leaves the most stubborn marks. Cigarettes, bidis, gutka, khaini and paan all stain brown to black, and they damage the gums at the same time, which matters far more than colour.
A less obvious one is mouthwash. Chlorhexidine rinses are excellent for a short course after gum treatment, but used for weeks on end they can leave a brownish film. And wherever plaque and tartar build up, usually along the gum line and behind the lower front teeth, stain has something rough to hold on to.
Most surface stain comes off with a professional clean and polish. Keeping up regular cleanings stops it from coming back as quickly.
When the colour comes from inside
Teeth naturally get darker with age. The enamel slowly wears thinner, so more of the yellow dentine shows through, and the dentine itself thickens and deepens in colour. Some people are simply born with yellower teeth or thinner enamel. That's genetics, not anything they did wrong.
Some stains go back to childhood. Tetracycline, an antibiotic that used to be given more freely, can leave grey or brown bands if it was taken while the adult teeth were forming. Too much fluoride at that age causes fluorosis, which shows up as white flecks or, in stronger cases, brown patches. It's common in parts of India where the groundwater is naturally high in fluoride.
Then there's the single dark tooth. If one front tooth has turned grey, particularly after a fall or a knock years ago, the nerve inside may have died. That tooth needs to be checked properly, not just whitened. Old fillings can be the culprit too: tooth-coloured fillings pick up stain as they age, and old silver fillings can make the whole tooth look grey. Brown or chalky patches can also be decay, which has to be treated before anything cosmetic.
Why it's worth knowing which is which
Because the fix is different. Tea stain responds well to cleaning and whitening. Tetracycline stain may only lighten partly, so bonding or veneers can be the better long-term answer. A dark tooth after an injury may need root canal treatment first, sometimes followed by whitening from inside the tooth. Before we suggest anything, we want to know the cause. It saves you spending money on something that was never going to work.
In the next post: why we always get your teeth and gums healthy before we do anything to make them look better.