Teeth whitening: what makes it safe, and when is it a mistake?

Why examination comes first

Whitening agents penetrate the enamel into the dentine. If there is decay or a crack in the tooth, the agent reaches areas it should not, causing sharp pain or nerve irritation.

If the gums are inflamed, contact with the agent causes burning and ulceration. This is why whitening is preceded by an examination and a clean, not as an arbitrary sequence.

Why teeth do not all whiten equally

Whitening works only on natural tooth structure. Fillings, crowns and veneers are manufactured materials that do not respond to the agent at all.

This means anyone with a front filling matched to their old shade will find it visibly darker after whitening. The answer is to replace the filling once the new shade settles, and this is a point to discuss before starting rather than afterwards.

Root-treated teeth also discolour from within and need a different approach from conventional surface whitening.

The problem with unprescribed products

Products sold without supervision vary widely in concentration, and some rely on abrasives that remove staining by scrubbing the enamel surface. The result looks good initially, but enamel is not replaced once lost.

Ready-made, non-custom trays are another problem, as they let the agent leak onto the gums. A tray made to fit your teeth keeps the agent where it belongs.

Keeping the result

The first days after a session matter most, because the enamel pores are relatively open and more ready to pick up pigment. Avoiding coffee, tea and dark sauces in that window makes a genuine difference.

Over the longer term, smoking is the biggest factor in staining returning, followed by daily consumption of dark drinks. The result needs a maintenance session at an interval your dentist sets.

This article relates to teeth whitening at My Clinic. For an assessment, book an appointment or message us on WhatsApp.