Teeth whitening: what actually works?

What causes teeth to darken

Most everyday staining comes from coffee, tea, red wine, and simply time — it sits on and within the enamel. Professional whitening lifts that kind of general staining safely. Deeper, internal discolouration (from an old injury or certain medications) behaves differently and may need another approach, which we’ll talk through honestly rather than over-promise.

Professional vs supermarket kits

Shop-bought kits are much weaker, and their one-size trays don’t sit evenly — so results are patchy and slow, and the gel can irritate gums. Professional whitening uses stronger gel, a custom fit, and dental supervision, which is both safer and far more effective. It also starts with a check-up, so any decay or gum problem is picked up first — the safeguard the kits skip.

In-chair vs take-home

• In-chair whitening is done here in a single visit, with your gums protected, for a noticeable lift on a timeline — handy before an event.
• Custom take-home trays are made to fit your teeth exactly, with gel to use at home over a couple of weeks — a gentler, gradual result you can top up later.

Both are options on our teeth whitening page — we’ll suggest the one that suits your teeth and timeframe.

What whitening won’t change

Whitening only works on natural tooth. It won’t change the colour of crowns, veneers or tooth-coloured fillings — so if you have those in visible spots, we’ll talk through what to expect first, and whether they may need matching afterwards. It’s also worth doing any planned crown work after whitening, so the new tooth is matched to your brighter shade.

Is it safe — and who shouldn’t?

Professional whitening on healthy teeth is a well-established, safe treatment. Some short-lived sensitivity is common and settles quickly. Whitening isn’t recommended during pregnancy, or where there’s untreated decay, gum disease or exposed tooth roots — which is exactly why it starts with a check-up rather than a syringe of gel. Results vary between people, and we’ll give you an honest idea of what to expect for your teeth.

How long results last, and how to keep them

Whitening isn’t permanent. Teeth pick up stain again from the same things that darkened them in the first place — coffee, tea, red wine, curry, smoking — so how long a result holds depends more on habits than on the treatment. Many people find a professional result lasts a year or two before it starts to fade, and a short top-up with take-home trays brings it back without starting from scratch. Rinsing with water after coffee or wine, using a straw for dark drinks, and keeping up regular cleans all stretch the interval.

When we’d say not yet

Whitening is done on healthy teeth, which is why it starts with a check-up rather than a gel. Untreated decay or gum disease needs sorting first, because bleaching gel on an exposed or inflamed area is uncomfortable and unhelpful. We generally don’t whiten during pregnancy or breastfeeding, or for children and teenagers whose teeth are still developing — not because harm is proven, but because there’s no good evidence of safety and no urgency. And if the discolouration is inside the tooth or on a crown, veneer or filling, whitening won’t change it; we’ll say so, and talk through what would.