Knowledge · Aesthetic Dentistry

Teeth whitening. What works, what does not and how to recognize a reputable treatment.

A factual classification of common whitening procedures. Active substances, prospects of success, risks and the difference between drugstore product and dental treatment.

Key takeaway

Whitening chemically lightens the tooth enamel and only works on healthy natural teeth, not on crowns, veneers or fillings. Every reputable treatment is preceded by a dental hygiene session, otherwise only the deposits rather than the teeth are lightened. How much lightening is achieved and how long it lasts is individual and depends on the starting findings and lifestyle.

Written by Dr. Fredrik Nord 22 April 2026 7 min read

What whitening really is

Whitening is not cleaning. Cleaning removes external deposits. Whitening changes the color of the tooth itself through chemical lightening of the tooth enamel. The active substance is hydrogen peroxide or carbamide peroxide in different concentrations, depending on the procedure.

Those who bleach without professional cleaning do not lighten the tooth but the deposits. That is the most common reason for unsatisfactory whitening results from drugstore products. Every serious whitening is therefore preceded by a dental hygiene session. Only on a cleaned tooth does the active substance work reliably.

Drugstore products versus dental treatment

In Switzerland whitening products for self-application are permitted with a maximum concentration of 0.1 percent hydrogen peroxide. That is medically a very low concentration with minimal effect. Strips, gels and pastes from the drugstore range deliver with correct application a very slight lightening of at most one shade level.

In dental practice we work with concentrations between 6 and 40 percent, depending on the procedure. These concentrations are only permitted in Switzerland under dental control and deliver lightenings of two to four shade levels. The decisive point is not the higher concentration but the controlled application with gum protection, findings check and individual adjustment.

In-office whitening, home whitening, internal whitening

In-office whitening

In a single session of one to two hours the active substance is applied to the tooth surface in high concentration. The gum is covered by a protective gel barrier. With some procedures the reaction is accelerated by light or laser, which, however, only marginally improves the effect. In-office whitening delivers the fastest result and is suitable for persons with tight time window or upcoming occasion.

Home whitening

We take impressions and fabricate individually thermoformed trays that fit the teeth precisely. You wear the trays at home overnight or for one hour during the day, filled with active gel. The treatment lasts ten to fourteen days. The end result is equivalent to in-office whitening, the effort for you is higher, the price lower.

Internal whitening

For a single dark-discolored tooth after a previous root canal treatment, surface whitening is not sufficient. In these cases the active substance is placed in the pulp chamber of the root-treated tooth and renewed across several sessions. The procedure is limited to individual teeth and delivers very good results with dark-discolored individual teeth.

When whitening does not work

Whitening works on healthy tooth enamel. It does not work on crowns, veneers, inlays or composite fillings. Those who apply whitening and have restorations in the front area risk a visible color difference between lightened own teeth and unchanged restorations. We discuss this in the assessment before whitening.

With tetracycline-induced discolorations from childhood, pronounced fluorosis or dentinogenic discolorations, whitening is often insufficient. In these cases we discuss veneers as an alternative aesthetic solution.

For patients with pronounced caries, exposed tooth necks or acute gum inflammation we postpone the whitening until the dental prerequisites are resolved. Those who bleach on inflamed gum risk intensified sensitivity and reduced effect.

Safety and side effects

Hydrogen peroxide and carbamide peroxide have been established in dentistry for decades and are considered safe with medically correct application. The most common side effect is a temporary sensitivity to cold and warm stimuli, which fades completely within 24 to 48 hours.

With contact with the gum a short-term white discoloration of the mucosa can occur, which also heals completely after a few days. We prevent this effect through careful gum protection before applying the active substance.

Long-term studies on multiply bleached patients have so far given no indications of structural damages to the tooth enamel. Prerequisite is application at dentally defensible intervals, usually not more often than annually or after individual indication.

How long the result lasts

One to three years, depending on lifestyle and oral hygiene. Strongly staining foods significantly reduce durability:

  • Coffee and black tea
  • Red wine and dark juice
  • Berries and tomato sauces
  • Tobacco in any form

Those who want to keep the result for a long time combine the whitening with annual dental hygiene and an adjusted brushing technique. A single refresh with home whitening trays every twelve to eighteen months keeps the result stable without a complete re-treatment being necessary.

What whitening costs

In Switzerland the costs move in the following bandwidths:

We bill according to SSO tariff. The costs depend on the procedure (in-office whitening, home whitening, internal whitening), the effort and material consumption. In-office whitening is usually more expensive than home whitening, internal whitening is billed per session.

Health insurance does not cover whitening because it is classified as a purely aesthetic treatment. You receive a written cost estimate from us before treatment begins.

When you should not have a whitening

During pregnancy and breastfeeding, because no sufficient study evidence on the safety of the active substances in this phase is available. For persons under 18 because the tooth enamel is not yet fully matured and the pulp cavity is larger than in adults. With acute caries or gum inflammation. With untreated root canals or open restorations.

In all other cases whitening is a safe and effective procedure with a well-documented history of effect and a clearly defined indication. Before treatment comes the findings. Those who bleach without findings lighten the wrong thing.

Frequently asked

Frequently asked

How much does whitening lighten the teeth?

That depends on the starting findings and the procedure. Dental procedures usually achieve a lightening of two to four shade levels, drugstore products considerably less. A particular final shade cannot be guaranteed because every tooth reacts differently to the active substance. We assess the possible result during the examination.

Is whitening harmful to the teeth?

Hydrogen peroxide and carbamide peroxide have been established for decades with medically correct application. Long-term studies have so far given no indication of structural damage to the tooth enamel. What matters is healthy starting findings, protection of the gum and sensible intervals, usually not more often than once a year.

How long does the result of a whitening last?

Usually one to three years, depending on lifestyle and oral hygiene. Coffee, black tea, red wine and tobacco shorten the durability considerably. With annual dental hygiene and an occasional refresh using home whitening trays, the result can be kept stable for longer.

Does whitening work on crowns, veneers and fillings?

No. Whitening only works on natural tooth enamel, not on crowns, veneers, inlays or composite fillings. Those who have restorations in the visible area risk a colour difference between their own teeth and the restorations after whitening. We discuss this during the examination before treatment.

When should you not have a whitening?

During pregnancy and breastfeeding, for persons under 18 and with acute caries or gum inflammation we postpone or refrain from whitening. With exposed tooth necks or open restorations we first resolve the dental prerequisites. Before every treatment comes the examination.

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