In short: Effective whitening uses peroxide compounds that lighten the tooth from within. Retail products are limited to very low concentrations and mostly remove surface stains only. Home remedies like baking soda or lemon do not whiten — they abrade enamel. Before any whitening, decay and gum inflammation must be treated, otherwise the agent reaches places where it causes harm.
Whitening is the treatment with the widest gap between what people want and what people know. Almost everyone has an opinion about it, and most of those opinions come from advertising.
How lightening actually works
Discolouration sits either on the tooth — from coffee, tea, red wine, nicotine — or in the tooth, as part of the natural colour, which darkens with age. Surface stains can be removed mechanically, and that is what a professional cleaning is for. Anything deeper needs a peroxide that penetrates the tooth and chemically breaks down the colour molecules. That distinction explains why some people are satisfied with a cleaning while others see almost no change despite whitening.
What does not work, or does harm
- Baking soda, bicarbonate, activated charcoal: abrasive. They polish briefly but with regular use they wear away enamel — which does not grow back. Thinner enamel lets the yellowish dentine show through more strongly: the long-term result is darker.
- Lemon and cider vinegar: acid decalcifies the surface. The effect is a roughened tooth, not a whiter one.
- Retail kits: limited in the EU to very low peroxide concentrations. Adequate for mild staining, not for real colour change.
- Offers without a dental examination: the actual risk. Without an examination, decay, leaking fillings and inflamed gums go undetected.
What must be settled first
Whitening belongs at the end of a treatment sequence, not the beginning. Decay must be restored, gums free of inflammation and fillings sealed. The reason is simple: through a leaking margin the agent reaches the inside of the tooth and can cause considerable discomfort. A cleaning also comes first, otherwise the peroxide works unevenly through the plaque.
One point is often overlooked: fillings, crowns and veneers do not lighten with the rest. If you have visible front-tooth fillings, they should be colour-matched after whitening — otherwise a new mismatch appears where there was none. If you are planning aesthetic work, whiten first and set the target shade afterwards.
Durability and sensitivity
How long the result lasts depends mostly on what is drunk and smoked afterwards — roughly one to three years, with wide individual variation. Temporary cold sensitivity during and shortly after treatment is common and subsides. With known sensitive teeth the concentration can be reduced and the application time extended; the result is the same, the route there just slower.
Whitening is not carried out during pregnancy and breastfeeding, or in children and adolescents whose tooth development is not yet complete.
Frequently asked questions
Does professional whitening damage enamel?
On current evidence, no, when carried out properly on healthy teeth. The peroxide acts on colour molecules rather than abrading the surface.
How white will my teeth get?
That depends on the starting shade and the cause of the discolouration. Several shades is realistic. A uniform brilliant white as seen in advertising is not achievable with whitening alone.
What about a single dark tooth?
A single dark tooth has usually had root treatment and discolours from within. That is lightened internally or covered with a veneer — a different procedure from whitening all the teeth.
Does German insurance cover whitening?
No, it is an aesthetic service and is invoiced privately.
This article provides general information and does not replace a dental examination. Medically reviewed by Dr. F. J. Rodríguez Ruíz, MSc., dentist at A+ Dental, Düsseldorf-Oberkassel.