There are four ways to whiten teeth. Two of them work, one is illegal in the UK, and the other is mostly a tax on hope.

Shop strips and toothpastes

Safe, cheap and limited. Toothpastes remove stains; they can’t change the colour of the tooth itself. Strips can shift a shade or two.

Salons and beauticians

Illegal for anyone who isn’t a dentist to apply whitening at an effective strength. If it’s strong enough to work, it’s strong enough to need a dentist.

Dentist-made trays

The best value: custom trays, professional gel, two weeks at home, 4–8 shades. You keep the trays for top-ups.

In-chair boost

Faster, not necessarily whiter. We use it for a wedding next week, not as a first choice.