Teeth whitening

The natural color of the teeth

As all people are different, the color of each individual’s teeth is just as much.

There are four families of natural color shades of teeth, as illustrated at right:

  • Auburn (reddish-brown) (A);
  • Yellow-reddish (B);
  • Gray (C);
  • Reddish-gray (D).

This palette includes the teeth colors of the vast majority of the population.

 White, a color that is not natural for teeth

Hoping to have completely clean white teeth is an impossible dream, regardless of those who think their favorite stars in magazines have teeth as white as their dentist’s lab coat!

Several factors can influence the color of a person’s teeth. The main factors are listed below.

The natural color of the teeth varies with age

The color of the teeth varies greatly from one person to another and it becomes darker with age. In fact, the dentine (under the enamel and naturally more yellowish) is becoming more and more exposed as the age of the teeth increases due to the gradual thinning of the enamel layer that protects the teeth.

The teeth therefore become more yellow or greyish with age.

The tobacco

Two substances contained in cigarettes are particularly known to create tough spots:

  • tar (dark);
  • nicotine (naturally colorless but becoming yellowish in reaction with oxygen).

Consumption of certain colored foods and beverages

Colorful foods and beverages contain chromogens (color pigments) that attach easily to the enamel of the teeth. They can be found, among others, in the following products:

  • coffee
  • tea
  • the Red wine
  • Dark soft drinks
  • Dark fruit juices (grapes, cranberries, etc.)
  • tomato soup
  • curry
  • the beets

Oral habits

A good brushing of teeth and frequent routine visits to the dentist can delay the appearance of spots on the teeth.

Some drugs

Some antihistamines (to counteract the symptoms of allergies), antipsychotics (to treat certain mental health problems), medicines against high blood pressure and tetracycline (antibiotic used against acne and bronchitis) stain teeth deep.

Chemotherapy and radiotherapy treatments of the head and neck may also cause a change in tooth color.

Indirect factors

Some indirect factors may also influence how a person perceives the color of their teeth:

  • The color of the skin: The darker the skin of a person, the more white the teeth will look. The color of the lips and gums can also influence the whiteness of a smile. It’s a question of contrast!
  • Make-up: As with the color of the skin, the darker the makeup will be close to the mouth, the more the teeth will appear white.

Brightness and type of lighting

For example, with a certain type of electric bulb, the teeth will look more yellow or whiter than with any other light source.

Depending on the time of day, the teeth will appear more or less yellow. Early in the morning, a bluish component present in greater quantity in the natural light outside will make the teeth appear whiter. In contrast, an orange component of the outside light at the end of the day will make them look more yellow.

Why bleach your teeth?

Today’s society is looking for beauty and some people want to improve their physical appearance to be well in their skin. A growing number of adults are turning to orthodontics to improve the aesthetics of their smile and achieve better masticatory function. People also want teeth whiter. Even if someone brushes their teeth two or three times a day and flosses once a day, these habits are unfortunately not enough to keep teeth white.

Dental bleaching is therefore a factor in restoring the radiance of a person’s smile.

Two types of whitening are offered:

  • home laundering with over-the-counter products;
  • professional bleaching in the dental office, sometimes including part of the treatment to be performed at home, under the supervision of the dentist.

In some cases, teeth whitening can make a noticeable difference on a person’s smile. In other cases, the results will be less important, depending on the nature of the spots on the teeth.

How it works?

The whitening agent acts on the surface of the tooth (enamel) and the dentin (located under the enamel).

It never reaches the pulp (inner part of the tooth) because it is not powerful enough to have an effect on it.

The most frequently used products for dental bleaching are:

  • hydrogen peroxide (hydrogen peroxide);
  • Carbamide peroxide;
  • urea peroxide.
  • The peroxide is able to “attack” the dark molecules that have accumulated on the enamel and dentine of the teeth in order to break them with the oxygen it contains.

Dental bleaching (also called dental cleansing)

This chemical reaction “clears” the teeth of one or more shades. In fact, some dentists use the term “dental lightening” to refer to dental bleaching. Since the tooth has a porous surface, the peroxide is able to break the ties that anchor the spots to the tooth.

Supervision of money laundering is necessary

The effect of bleaching is directly proportional to the concentration of the bleaching agent used; In theory, the higher the concentration, the more effective the product will be. A dentist must supervise a process of dental lightening when the concentration of the bleaching agent exceeds a certain percentage. The duration of the treatment also depends on the color of the teeth and the origin of the coloration. For example, the darker the teeth, the longer it will take to blanch.

The dentist remains the only specialist who can recommend the dosage of the bleaching agent used. Some products can be applied for a few minutes and others, up to 90 minutes, one to two times a day. There are also products that must be used overnight as they act more slowly.

Know before undertaking money laundering

Regardless of the bleaching technique used, a person who wants to whiten his teeth, even with over-the-counter whitening products, should consult his general dentist beforehand.

The latter will be able to help you put all the chances on your side to maximize the quality of the result of your whitening

Here are the actions that should be taken by a dentist before laundering:

  • Perform an examination of your mouth, cleaning and scaling. Indeed, a teeth devoid of plaque and tartar will be able to better absorb the bleaching agent.
  • Check the color of your teeth and tell you if a whitening will improve their color.
  • Determine with you if there are contraindications to bleaching.
  • Determine the current (reference) color of your teeth so that you can compare the bleaching results with the reference color. Without the starting color, it will be difficult to evaluate the whitening of your teeth. It should be noted that before and after intraoral images, without the reference color close to the teeth, are not very useful for comparison purposes, as the lighting may not be the same Two photo sessions.

White, pristine teeth are not the reality …

No bleaching technique can lighten the color of the teeth beyond their natural color. The enamel of the teeth of certain persons is, moreover, naturally more yellowish than that of other persons. Realistic expectations of tooth whitening are therefore needed.

An oral health professional can help you determine these expectations.

What should we expect as a change in tooth color?

An improvement of two to three shades can represent a visible difference on a smile that has lost its shine over time. Dental bleaching normally leads to a change from two to seven shades.

Yellowish teeth usually respond better to whitening than greyish teeth.

Whitening products will have no effect on artificial crowns (including crowns and bridges on implants and veneers), partial and complete dentures and composite resin restorations (white fillings).

Restore white color to blackened teeth

It is possible to give a whiter color to the teeth that have blackened as a result of a root canal treatment. This type of whitening is called “non-vital”, since teeth blackened in this way are considered devitalized (non-living). A brightener from the inside to the outside of the tooth structure is required and only an oral health professional can help you do so. Traditional whitening products will have no effect.

The results of dental bleaching only last from six months to two years and depend on the oral hygiene of the person.

Take precautions when tooth whitening

It is still impossible to know the long-term effects of repeated use of the whitening products on the teeth. There are very few studies on the subject because dental bleaching is a relatively recent practice. In addition, some experts are concerned that some of the peroxide used to bleach teeth is swallowed and digested by the patient. The long-term risks of too much ingested peroxide, such as repeated bleaching, are still unknown. Patients are therefore advised to use these products with caution, preferably under the supervision of a dentist, and to avoid bleaching on a regular basis or for too long a period of time.

Observe prescribed bleaching frequency

It is not advisable for anyone to whiten their teeth more than once a year, with at least one stop of the use of the whitening products for six months.

To maximize the investment of time and money needed to whiten her teeth, a person must pay attention to what she eats and drinks after a dental lightening procedure.

In the case of the use of carbamide peroxide as a bleaching agent, it is preferable to use a lower concentration (eg 11%) over a longer period of time per day rather than a higher concentration (eg. : 16%) over a shorter daily period.


Although dental bleaching is a safe procedure for many people and without serious consequences, there are still contraindications that must be taken seriously.

The tobacco

Tobacco contributes significantly to yellowing of teeth. A patient who smokes and undertakes dental bleaching without intending to quit smoking during or after the procedure does not make his or her investment worthwhile. It is always best to tackle the cause of discoloration of the teeth, ie to stop smoking!

Smoking may also constitute a contraindication to the use of bleaching agents. Indeed, the European Commission’s Scientific Committee on Consumer Products (SCCP) considers that “hydrogen peroxide can act as a weak” cancer promoter “, that is, it can slightly stimulate Growth or multiplication of cancer cells “(source: Protégez-vous, June 2011). Since smokers are already at higher risk of developing oral cancer, this risk for peroxide should be considered when dental bleaching done on a smoker.

For its part, the International Agency for Research on Cancer states that the amount of peroxide in bleaching products is too low to be considered carcinogenic in humans (source: GreenFacts, 2008).

Get the advice of an oral health professional first

It is important to seek the advice of an oral health professional before undertaking a dental clarifying procedure if:

  • you experience dental or gingival sensitivity when eating or drinking hot or cold foods;
  • you have an unpleasant feeling of cold on your teeth when you breathe in your mouth;
  • you have recently received a restoration treatment (filling, root canal treatment, etc.) or plan to receive one soon;
  • oral or gingival infection is present;
  • ulcers, abscesses, redness, swelling and / or bleeding of the gums are present;
  • the medications you take have discoloured your teeth.

Absolute contraindications

A tooth whitening treatment should never be undertaken under the following conditions:

You are a person under the age of 12 or whose permanent teeth eruption is not complete.

You are pregnant or nursing (peroxide can cross the placental barrier and affect your fetus and it may also end up in your breast milk).

Ideally, people under the age of 18 should not be treated for bleaching.