Teeth Whitening Facts and Myths

Why Teeth Get Dark

There are many causes of tooth discoloration. The most common include genetics, aging, consumption of staining substances (smoking, coffee, tea, and colas), tetracycline (antibiotic) staining, excessive fluoride, and old fillings. Whitening toothpaste can remove stain that is on the outside of the teeth. Dentists call this extrinsic staining. However, whitening toothpaste and professional dental cleanings will not change the color or intrinsic staining of the teeth. That is why tooth whitening (sometimes called tooth bleaching) is so popular

Here’s How Tray Teeth Whitening Works

A whitening gel is placed in a tray that fits over your teeth. As the active ingredient in the gel, carbamide peroxide, is broken down, oxygen enters the enamel and bleaches the colored substances. The structure of the tooth is not changed; only the tooth is made lighter and whiter. Fillings, Crowns, and Bonding will not lighten.

The fit of the tray is critical to success of treatment. Impressions are made by your dentist. Accurate models of your teeth are obtained from which custom fitting whitening trays can be made.

How Safe is This?

Dentists have known for years that tray whitening or bleaching is a fast, safe and predictable way to whiten teeth 2-5 shades in a matter of days.

What is the difference between laser whitening and custom mouthpieces?

Laser is done by a dentist who applies a 35% Hydrogen Peroxide solution on your teeth. Once this solution is on, a light is held a couple of inches away from your teeth to speed up the chemical reaction of the Hydrogen Peroxide. Many dentists advertise that this works better than tray type whitening. There is NO clinical data to indicate the laser whitening works any better than tray whitening. NONE! The problem with this procedure is that after a year of your normal eating habits (drinking coke, tea, coffee, etc.) your teeth become slightly discolored again and develops a new stain. With the laser whitening, you will have to go and pay $500 plus to have white teeth again. With the custom mouthpieces, you already have the custom mouthpieces that you can wear a year later for a night to take off the new stain at no cost.

How Does the Tray Whitening System Compare to Crest Whitestripes?

Crest White Stripes are a new plastic strip that is coated with Hydrogen Peroxide and placed across the front teeth. The strips do work…sort of. Tests by Crest show that teeth are lightened an average of 1 to 2 shades. They tend to whiten only the front teeth while and the visible premolars are still dark.

How Long will Whitening Results Last?

For most people, the treatment is long-lasting. Exposure to coffee, smoking, red wines, and some medicine products will gradually darken teeth again over time. After an initial treatment, most people do touch-ups one day about every 3-6 months.

How long will it take and How white will they get?

When wearing the trays Carbamide Peroxide is slowly broken down to Hydrogen Peroxide which whitens the teeth. The 16% gel whitens more slowly but causes less tooth sensitivity. The 22% gel whitens quickly but can cause temporary sensitivity to temperatures. Both the 16% and 22% gels need to be worn for about 10-14 days to achieve maximum whiteness.

Virtually everyone who whitens their teeth will see improvement.

The ultimate whiteness will be determined by the length of time the teeth are exposed to the whitening gel and the mineral composition of the teeth. Teeth whitening is kind of like a reverse suntan. Some people get great results in only one or two days while others need more treatment time.

The American Dental Association (ADA) has recently made public a review by the Cochrane Collaboration of 25 studies of home-use tooth whitening products. The 25 clinical studies looked at the effectiveness of home-use whiteners including:

Home whitener kits given out by dentists
Over-the-counter whiteners
They looked at all forms of tooth whiteners except whitening toothpastes:
Films (which are painted on the teeth)
Gels (applied in trays)
Strips (applied to the teeth)

The tooth-whitening agents used by all the products were either carbamide peroxide; or hydrogen peroxide Each home-use tooth whitening product was used for two or more weeks. After two weeks, the teeth looked whiter than if no whitening product had been used, and differences in effectiveness were due to levels of active whitening agents in the ingredients. Store-bought kits have weaker whitening agents.

Bias in the studies

The Cochrane review noted that all 25 studies were conducted by manufacturers of tooth-whitening products and had “moderate to high levels of bias”. They also noted that reviewing these studies of at-home users was particularly difficult, “given the significant variation in whitening products, concentrations of active ingredients, study designs and application methods.” The reviewers also called for some long-term studies (at least 6 months) of at-home tooth whitening, to evaluate its potential health effects, and effectiveness.


Tray teeth whitening procedures have been common in dentistry since the late 1980’s. The procedure typically takes about 1-14 days to complete. Side effects are minimal. The most common side effect is tooth increased sensitivity particularly to cold. These symptoms go away when whitening is discontinued.

Tooth whitening is currently the safest and most conservative dental cosmetic procedure. As dental care is moving from being a boring chore to another way to be glamorous the popularity of this treatment is sure to continue.

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