Whitening changes the colour of natural teeth with peroxide — in the chair at a controlled concentration, or at home in a custom tray over two to four weeks. It does not change the colour of crowns, veneers or fillings, and that limit shapes the whole plan.
Most healthy adult teeth respond to some degree. What varies is the type of stain, the starting shade, and whether the colour sits in the enamel or deeper inside the tooth.
Crowns, veneers, composite fillings and bonding do not lighten. Whitening a mouth with visible restorations can leave them looking darker by contrast; either they are replaced afterwards, or the shade is matched to them instead.
The two approaches use the same chemistry at different concentrations. Which one suits you depends on how much time you have and how your teeth react.
A high-concentration hydrogen peroxide gel — typically 25–40% — applied with the gums isolated and the lips retracted, in three or four cycles of 10–15 minutes. One visit, fastest result; sensitivity usually peaks the following day.
Impressions are taken and trays made to fit. Carbamide peroxide at 10–16% is worn for 30–60 minutes a day, or a weaker gel overnight, for two to four weeks. Slower and gentler, and the result is often more even because the gel reaches the whole arch.
A chair session to lift the base shade, then trays at home for a week or two to even out the neck of the tooth, which is usually the darkest part. This is the plan most patients end up with.
Decay, gum health and existing restorations are checked. Scaling and polishing come first: whitening does not remove calculus, and a clean surface is the only fair starting point.
Photographs and a shade reading under standard light, taken before anything begins. Without this, the change can only be argued about, not measured.
Either a single chair session with gum isolation, or trays and written instructions. With trays, the first two or three days show whether your teeth are sensitive and the gel strength is adjusted accordingly.
The colour stabilises over about two weeks as the teeth rehydrate, so the final shade is judged then — not on the day of treatment, when teeth always look unnaturally bright.
Top-up trays every six to twenty-four months, and a sensible first 48 hours: no coffee, red wine, turmeric or smoking while the enamel is most receptive.
Whitening is low-risk when it is assessed and supervised. Most of the problems come from doing it without either.
More gel does not mean whiter. Repeated high-strength sessions without review increase sensitivity and give the enamel a chalky, thin appearance; the tray instructions exist for a reason.
At supervised concentrations, no: peroxide lifts pigment without dissolving measurable tooth structure, and the mineral recovers in the days afterwards. Abuse — frequent high-strength sessions with no assessment — is where damage and lasting sensitivity come from.
It cannot be promised in advance. Yellow and age-related staining responds best; grey, tetracycline-related and fluorosis staining responds poorly and sometimes not at all. Most patients gain a few shades, and the honest answer is a range rather than a number.
The gel itself is not painful. Sensitivity to cold, and occasionally a sharp ache at the neck of the tooth, is common for a day or two — reduced by a lower concentration, a shorter wear time, or a desensitising gel before the session.
Six months to two years for most people. Coffee, tea, red wine, turmeric and smoking bring it back faster; a hygiene visit every six months and the occasional top-up tray keep it steady.
A photograph taken near a window, without a filter, is usually enough to say which kind of stain you have, whether whitening is likely to work, and whether restorations need to be planned around it.
General information, not medical advice. Suitability can only be judged after examining the teeth and gums and reviewing the medical history; results vary between patients.
