Tooth Whitening

How does Tooth Whitening Work?

Tooth whitening, or dental bleaching, is one the fastest and easiest ways to improve your appearance and put more sparkle in your smile. With tooth bleaching your teeth look younger, healthier and brighter.

The part of the tooth you can see directly in your mouth is the enamel layer. This is the only part of the tooth that should be above the gums.  The normal color of enamel is white, but it is translucent and the color of the other parts of the tooth underneath the enamel can show through.

The stuff immediately under the enamel is called dentin.  It is usually a yellow color, but it is porous, and materials from the nerve can go through it causing the color to change to a brownish yellow as you get older. The color you see when you look at a tooth in your mouth is a combination of the colors of the enamel, which may permanently stain as we get older, and the dentin underneath it, which darkens over the years because it is close to the nerve underneath.

This is the reason that only brushing your teeth will not prevent them from becoming darker yellow as you get older. That is why tooth whitening is the only way to brightern your smile. You can brush until you're blue in the face, but you will not be able to brush off the normal color your teeth are supposed to be. 

That is where the tooth whitening process comes in.  The tooth whitening gel is usually hydrogen or carbamide peroxide that breaks down into oxygen molecules. These molecules go into the tiny pores of the enamel and dentin, and break up the stains that block out the light.

As the stains are broken into smaller and smaller pieces, more light passes through the teeth and makes them look lighter. Stains that are built up over time that are yellow or brownish give the best results. Teeth that are dark brown to blue-gray are the most difficult to bleach because the stain is deeply set into the tooth’s structure.

Root canal treated teeth can be dark because the dead nerve which triggered the root canal treatment often leads to a darkening of the tooth to a dark brown color.

At our Seattle dentist office in Bellevue, Washington we offer custom take-home bleaching kits. Call us at (425) 454-2005 to schedule an appointment. We have considered offering in-office bleaching techniques but have chosen not to use these because they are much more expensive for you and bleaching kits are still required whether or not you do in-office bleaching. So, for half the price just purchase the custom bleaching kit.

We do recommend using a custom bleaching kit made by a dentist versus the store-bought kits because the results from all of the over-the-counter methods are not as good as what you can get from your dentist.  The reason for this is that the dentist can provide prescription strength bleach and custom bleaching trays that fit your teeth tightly and keep the bleach in undiluted contact with the teeth for long periods of time. Neither bleaching strips nor the stock trays provided in the over-the-counter bleaching systems have either of these advantages. Again, we offer custom bleaching kits so please call.

Is bleaching safe?

8 out of 10 dentists now offer tooth whitening, or bleaching, as an aesthetic treatment for their patients. The American Dental Association has published the following statement:

"Dentist-prescribed, home-applied bleaching made by a reputable manufacturer and used under the supervision of a dentist in a relatively short-term treatment duration is safe and recognized as most effective in lightening the color of teeth. Bleaching materials that have received the ADA Seal of Acceptance are recommended.

Mild thermal sensitivity [sensitivity to cold] is a common side effect associated with most in-office and dentist-prescribed home bleaching methods. However, no long term irreversible tissue effects have been demonstrated in relevant clinical studies." 

What about tooth sensitivity?

Tooth whitening solutions do make your teeth sensitive for a short period of time, usually not more than 24 hours and not everyone has this experience.  For the bleaching to be permanent, the solution must pass through the enamel to reach the dentin. Dentin has microscopic tubules which allow the flow of cellular fluids between the living nerve in the center of the tooth and the outer layer of enamel. 

This is the reason that the teeth may become sensitive.  The sensitivity usually goes away within 24 hours of stopping the bleaching treatments, and the nerves in the teeth do not experience permanent damage. Tooth whitening is safe. Please call our Seattle dentist office in Bellevue, Washington at (425) 454-2005 to ask any questions you may have.

What tooth whitening can't do

• Tooth whitening will not bleach out the black, brown or white color imparted to teeth due to decay.  Teeth should be repaired before bleaching is performed.


• Tooth whitening will not bleach out dark areas left on your teeth by old amalgam fillings.  Taking out the old metal filling and putting in a new composite will usually fix this, but if the tarnish has soaked deeply into the tooth structure, the tooth may remain permanently discolored.

• Tooth whitening will not generally help with fluorosis. Dental fluorosis is an irreversible condition caused by taking in too much fluoride during the tooth forming years. It is the first visible sign that a child has had too much fluoride. You may have fluorosis if you grew up in a part of the country (before the 1960's) that had a lot of fluoride in the drinking water.

• Tooth whitening is not effective in reducing the irregular gray horizontal lines seen on patients with tetracycline stain in their tooth.  Tetracycline stain is seen mostly in older patients who received tetracycline to treat ear infections when they were young.  Doctors in those days did not know that this drug would affect developing teeth of children causing this deformity. Minocycline, which is often used to treat acne, can also cause your teeth and gum tissues to turn dark. Unfortunately, bleaching will not remove this stain from your teeth.

The different forms of Tooth Whitening

Whitening toothpastes

These are over-the-counter whiteners that have a small amount of carbamide peroxide.  These toothpastes will work to brighten your teeth if you are a very good brusher, brush many times a day, and have a lot of patience.  They can help keep your teeth white after you have had your teeth bleached. 

Dentist-prescribed bleach in custom made trays 

This is the product you get at the dentist's office.  The bleaching product can only be bought with a prescription and has to be used with the custom trays that the dentist makes for you. This system produces very good results in a relatively short period of time because of the high concentration of the product. Also, because the custom made trays keep the bleach close to your teeth, the results are great.

Bleach releasing disposable strips (Crest Strips) 

These are strips of plastic that stick to the teeth and are worn for several hours.  The bleaching concentration in the over-the-counter products is quite a bit lower so it takes a lot longer to get the same results. The main advantages to the strips are that no impressions need to be taken to make trays, and the strips do not apply pressure to the teeth which may increase the sensitivity of the bleaching process. However, the surface area of the contact is narrower with the strips and they can be difficult to effectively bleach the lower teeth.

In-office bleaching (Power bleaching)

Some offices offer a quick start bleaching procedure where a concentrated peroxide gel is put on the teeth and allowed to remain in place while "activated" with a light source. These treatments are more expensive because they are done in the dentist’s office. 

In our Seattle dentist office, we recommend the take-home tray method because you can get the same or better results with much less cost. We recommend the custom bleaching kit from a dentist because the trays used fit your teeth properly and improve the bleaching results.

The tray method can get the same or better results and it allows you to choose how much bleach you want to use. You can use the trays as long as you want, and keep them around for touch-ups later. When you come see us we will recommend the most effective form of bleaching for you, both in cost and results.

Light or laser bleaching:

In-office bleaching systems use a gel made with a 35% solution of hydrogen peroxide instead of the carbamide peroxide used with trays or strips in the take-home systems.  The hydrogen peroxide is much stronger than the carbamide peroxide solutions used in take-home systems, however it must be put on by dental staff because of the potential damage to other parts of the mouth surrounding the teeth. 

This stronger hydrogen peroxide offers very effective tooth bleaching in about two hours on its own, however, most dentists speed up the process by using a heat or light source to release more oxygen from the gel faster than would happen without the light.  Manufacturers of these solutions have managed to cut the time down to about one hour, or in some cases even to a half hour if the light or heat source is used to accelerate the process. Just remember that it is more expensive and not usually much better than a cusom take-home bleaching kit.

Can I get the same results with store-bought bleaching products as I can from the Dentist?

The results from all of the over-the-counter methods are not as good as what you can get from your dentist.  The reason for this is that the dentist can provide prescription strength bleach and custom bleaching trays that fit your teeth tightly and keep the bleach in undiluted contact with the teeth for long periods of time. Neither bleaching strips nor the stock trays provided in the over-the-counter bleaching systems have either of these advantages.

However, one advantage to having over the counter bleaching products available is that once you finish a dentist-prescribed bleaching, you get to keep your custom trays. You can do touch-ups using the relatively less expensive bleaching solutions available from commercial sources.

When you come see us we will recommend the most effective form of bleaching for you, both in cost and results. Please call us at our Seattle Dentist office in Bellevue, Washington at (425) 454-2005 to schedule an appointment. We look forward to meeting with you.