12 June 2026 · 6 min read
How whitening actually works
Peroxide gel penetrates the enamel and breaks down the pigmented molecules inside the tooth. Anything that does not contain an effective peroxide simply polishes the surface — it cannot change the internal colour of the tooth.
Charcoal and abrasive pastes
These remove surface stain by abrasion. Used long term they wear enamel and can make teeth look more yellow, because the darker dentine beneath begins to show through.
Online whitening kits
The main risks are ill-fitting trays that leak gel onto the gums, and unknown concentrations. Uneven results and chemical burns to the gum margin are the common outcomes we see and have to correct.
What we recommend
A supervised in-clinic session to lift the bulk of the discolouration, followed by custom-made trays for controlled top-ups at home. Crowns, veneers and fillings will not change shade, so their replacement should be planned after whitening.