15 Aug
Before and After Teeth Whitening Photos

How Teeth Whitening Works

Have you ever wondered how teeth whitening works or if it will work for you? This post will talk about how the products chemically work to give the appearance of a lighter brighter smile as well as the whitening process in the office vs at home with custom trays.

Teeth are porous, making it easy for the two first layers of your teeth to absorb bleaching agents. When a bleaching agent is applied to the teeth the color is oxidized by free radicals or oxygen molecules that pass through the enamel and dentin, breaking up the staining molecules in the tooth and giving it the appearance of a lighter shade.

Whitening can be achieved with either a hydrogen peroxide or a carbamide peroxide or on occasions a mixture of both. Hydrogen peroxide is fast acting and releases a strong dose of whitening power within the first 15-30 minutes after activation and dies off quickly. Whereas carbamide peroxide releases its whitening power slowly and only to 50% within the first 2 hours after activation and can remain active for up to 8 hours. Both ingredients can achieve the same results but depending on your individual case it will be decided which one would be better for you or if a conjunction of both is necessary.

Whitening does not work the same on all teeth, so it may not correct some types of discoloration. For example, yellow teeth will probably respond better to whitening treatment than will brown teeth, and teeth with gray discolorations may not respond at all. Bleaching agents will not whiten veneers, crowns, or fillings. Teeth whitening alone will not be effective on tooth discolorations resulting from tooth injuries or root canal treatment. These situations require additional steps that your dentist can help guide you through.

It is important to realize that teeth whitening is not always a one and done treatment and sometimes depending on your situation it could require a few visits.

Understanding Teeth Staining

There are 2 types of staining: intrinsic and extrinsic. A dental professional will be able to distinguish between the two and make a whitening treatment plan that is best for you.

Extrinsic staining: happens on the surface of the teeth and can be easily removed with whitening. Examples of this include stains from foods, drinks, and tobacco products.

Intrinsic staining: happens within the tooth and is much harder to lighten. This type of staining occurs from inside and although it can be changed, it does take more time.

Fluorosis and tetracycline staining are the two hardest to lighten because they lay deep in the tooth and have progressed with time. Fluorosis staining comes from being exposed to too much fluoride at an early age, while tetracycline primarily comes from prescription antibiotics used years ago and made the teeth either a blue gray or yellow brown color.

Whitening Gel and Custom Teeth Whitening Tray

In-Office Teeth Whitening

With the help of your dental professional, a customized whitening plan for your individual case. In-office whitening utilizes a hydrogen peroxide and is a good option for candidates with both intrinsic and extrinsic staining. The only reason one may not be a good candidate would be underlying dental issues such as existing periodontal issues, open areas of decay and overall oral health.

If sensitivity is an issue prior to whitening, there are steps that can be taken prior to and post whitening that will help aid in a successful whitening visit with little to no sensitivity. With one session you can expect to see an instant change that will range between 2-6 shades lighter.

At-home custom trays can be fabricated at the time of this appointment to help not only with the maintenance of your result but also to continue the process of whitening immediately after your session to get an even brighter result.

Custom Bleaching Trays

Compared to in-office whitening, this treatment is done at home with a carbamide peroxide in a tray that is fabricated to fit your teeth perfectly. Because this treatment utilizes a carbamide peroxide gel, the results take a longer time to achieve but ultimately the same results can be achieved IF the treatment guidelines are followed. Your dental professional will give you instructions not only on how to fill your tray and protect your gum tissue but also for how long to wear these trays and food/drinks to avoid while doing it.

With at-home treatment solely on its own, it is extremely important that the patient wear these trays as discussed at the time of their appointment, and to wear them consecutively without missing a day. If a patient is not sure if they will be able to commit to wearing their trays for the timeline discussed, then treatment will be compromised, and final results will not reach their full potential.


Heni Tufa

Dr. Tufa is a general dentist in Acton, MA who is also an Invisalign Provider and certified Botox dentist.