Sharp, second-long zings after whitening are a reversible pulp reaction that settles in two or three days — unless they are coming from one specific tooth.
Whitening sensitivity is a short, sharp shock lasting a second or two, and it comes from peroxide passing through enamel into the dentinal tubules and reaching the nerve, producing a brief and reversible inflammation of the pulp. It is not damage. It typically starts a few hours after the session, peaks within the first twenty-four hours and settles within forty-eight to seventy-two. Many patients notice nothing at all, and most of those who do describe it as annoying rather than painful.
Sensitivity is largely predictable, which means it is largely preventable. We check for exposed root surfaces, cracks, leaking old fillings and untreated decay first, because those are the teeth that hurt afterwards, and each of them is treated before whitening is booked at all. Patients who already report cold sensitivity start a potassium nitrate desensitising toothpaste two weeks before the appointment, and a fluoride varnish goes on immediately after the last gel application.
Avoid ice, very cold drinks and anything scalding for two days; the tubules are temporarily open and thermal stimuli travel straight down them. Skip whitening and combined sensitivity-whitening toothpastes during this window and use a plain fluoride paste instead. A standard anti-inflammatory painkiller taken an hour before the session lowers the peak for patients who have had trouble previously. Do not stack a second session onto the following day to chase a brighter shade.
There is one pattern we ask you to report. Generalised sensitivity that fades over two or three days is normal bleaching behaviour. Pain localised to a single tooth, lingering more than thirty seconds after cold, or still present a week later is not caused by the whitening — it is a crack or an inflamed nerve that the peroxide has revealed. That tooth needs assessment, and root canal treatment starts at €120 if the pulp is involved.
No. It is a reversible inflammation of the pulp and in the great majority of cases it has gone within seventy-two hours. Sensitivity that persists beyond a week points to a different problem in one specific tooth and should be examined.
Usually yes, with preparation: two weeks of desensitising toothpaste beforehand, a lower gel concentration, shorter application times and fluoride afterwards. If the sensitivity comes from exposed roots and receding gums, we treat that first.