Dr. Beatrice Leung Dentistry Professional Corporation

Dental Professional? Click Here

Teeth Whitening

“I’d Like To Know More About Teeth Whitening”

Written by Dr Beatrice Leung
In my practice in Toronto, many patients ask me about teeth whitening in one-way or another. Teeth Whitening has definitely become a very popular treatment that can brighten up your smile quickly. Both online and local retail stores have countless teeth whitening products to entice you, the customers, into buying. But how do you decide whether you are a suitable candidate for teeth whitening. And if so, which product would best work in your case. Over the years, what I have noticed is that many of the patients asking about whitening treatment actually do not benefit from dental teeth whitening. While teeth whitening can definitely improve many people’s smile, it is not for everyone. Before you go out and purchase the next best teeth whitening product, perhaps you need to educate yourself what is it that you don’t like about your smile first.

For people who had very little dentistry, had fairly straight teeth, but noticed that their teeth have gotten more yellow with time, then teeth whitening will be the most conservative treatment to try. Shown below are pictures of teeth that would be suitable from teeth whitening.

Teeth suitable for Whitening

ideal teeth for whiteningThe truth is our teeth, like every part of the body, are subject to normal wear and tear. Due to the natural colour of our tooth structure, they also get more yellow with time. Also, if you tend to drink a lot of coffee, tea and wine, then your teeth may have had a lot of extrinsic stains. Fortunately, dental cleaning and polishing can remove most of these stains. Some toothpastes will market themselves as “whitening” toothpastes, but they are just regular toothpastes that contain more abrasive ingredients to facilitate the removal of stains. These abrasive ingredients may wear away your tooth structure prematurely making your teeth more sensitive with time. In any case, without properly removing these stains, your teeth will stay discolored even if you try different forms of tooth whitening products. So before embarking on trying different teeth whitening products available, the first step is to remove these stains and see if you are satisfied with the appearance of your teeth.

Teeth with Extrinsic Stains before dental cleaning and polishing                            
teeth with extrinsic stains
After dental cleaning and polishing
teeth after cleaning and polishing

Types of Whitening Products

There are many different teeth whitening products out there. There are the professional in-office dental whitening products available at most dental offices, and then there are those over the counter teeth whitening products available at local retail stores or online stores. These products range from a variety of whitening toothpastes, whitening strips to whitening trays with different concentration formulation gels. Most of these formulations gels contain the active ingredients of carbamide peroxide and/or hydrogen peroxide. Depending on where you purchase them, they usually come in various concentrations. Most of the over the counter products will have a lower concentrations of these active ingredients. The ones available in the professional dental offices will have a higher concentration.

There are also laser teeth whitening systems, which claim to give the result of an accelerated whitening process. These systems used to be only available at professional dental settings. Recently, new over the counter products have incorporated light activated whitening systems as well.

types of teeth whitening products

How does Teeth Whitening Work?

Most in-office whitening products take 30-90 minutes per visit requiring on averages 1-3 visits to complete the treatment. A protective gel or rubber dam is applied around your teeth to protect them from direct contact with the active ingredient of the bleaching agent. This bleaching agent is then applied and/or “painted” onto the surface of your teeth. The bleaching agent may then be further activated either through heat or high-intensity lights to enhance the whitening process. Such in-office whitening treatment may cost between $300.00-$800.00.

As for the in office take home whitening products, the bleaching agent, usually in the form of a gel, is applied to a custom-fitted tray. The patient will wear this custom-fitted tray with the gel in it. Depending on the concentration, the tray may be worn for a few hours or may be worn overnight. The treatment will usually last no more than two weeks. Typically, professionally purchased home whitening products including the custom-fitted trays may cost in the range of $200.00-400.00. Other home whitening products purchased at local retail stores or at online stores may cost anywhere from $20.00-200.00.

These teeth whitening products all work in one way or another if they have the correct active ingredients and their concentrations. In theory, products with a higher concentration of the active ingredients may work faster. However, there are no best teeth whitening products out there. The effectiveness depends on the natural tooth structure. The smaller the teeth, the easier is the active ingredient to reach the tooth structure. Likewise, the more porous the teeth, the easier it is to reach the tooth structure. The results are variable and may last only for six months.

In any case, the bleaching agent, which is a peroxide-generating compound, whitens the surface tooth structure of enamel and the next layer of dentin. These teeth whitening products, whether they are purchased at professional dental settings or over-the-counter retail stores, have been shown to cause sensitivity. Fortunately, such sensitivity is only temporary. In addition, based on the current scientific evidence, there is no concern about the adverse effects on tooth structure or enamel hardness.

Shown below are sample cases where teeth whitening have been used.

Before Treatment (only bottom teeth can be whitened)                          
teeth before treatment

After Treatment(only bottom teeth can be whitened)
after teeth treatment

In the above case, the patient is replacing her old bridge on the top front area.  Before replacing the bridge, she received two weeks of home-whitening treatment with 20% carbamide peroxide purchased at our office.  The bridge being made of porcelain will not be whitened; therefore the colour of the top bridge remained stable throughout the whitening treatment.  The lower teeth are the ones that can be whitened. Notice the whitening is not uniform throughout the teeth. The part closer to the gum, although lighter in colour, remained more yellow because there is less enamel covering the tooth. The part closer to the top became noticeably whiter because there is more enamel structure on that surface. Enamel tooth structure is what gives the tooth the white translucent colour. Now that the lower teeth have been whitened, the top bridge can be safely removed and replaced with a new bridge that matches the colour of the lower teeth.

Before Treatment 
before whitening with missing tooth

After Treatment
after whitening with crown

In the above case, the patient lost his front tooth from an accident. He received an implant crown to replace the missing tooth. Prior to replacing that tooth, he received two weeks of home-whitening treatment with 20% carbamide peroxide purchased at our dental office. The immediate brightness and whiteness can be appreciated by comparing the before and after treatment photos. You may also notice that the colour of his teeth is not uniform. In fact, if you look closely enough, you will see tiny white streaks and specks throughout the surface of the enamel. These are evidence of hypocalcification of the tooth structure, which may be caused by a variety of things. The most common cause would be excessive exposure of fluoride during teeth development. Teeth whitening will not remove these tiny white streaks and specks but can brighten up the yellow part of the tooth structure.

Teeth Not Suitable For Whitening

As mentioned at the beginning, teeth whitening treatment is not for everyone. Some teeth have unique structural problems where dental teeth whitening will not be able to correct. Some of these problems are:

  • Teeth with old fillings
  • Teeth with extensive recessions
  • Teeth with hypocalcfication (fluorosis)
  • Teeth with craze lines
  • Teeth with uneven arrangement
  • Teeth with old fillings and crowns


Teeth with Old Fillingsteeth with old fillings

Teeth with old fillings do not get whitened. The actual tooth structures get whitened but the material of the filling does not. As a result, the contrast between the filling and the tooth will become more apparent. In these cases, it is recommended to replace the fillings once the teeth whitening treatment has been completed.

Teeth with Extensive Recession

teeth with exctensive recessionTeeth with recession present the unique problem where the root of the tooth is much more exposed.The root, being made up of mostly cemental and dentinal tooth structure, is naturally more yellow than enamel. Teeth whitening can whiten these tooth structures but may also make the teeth much more sensitive. In some situations, gum grafts may be considered to cover up these exposed roots, which may decrease the amount of yellowness that is shown in your smile.

Teeth with Craze Lines

These craze lines are tiny cracks that occur on the outer layer of enamel tooth structure. They do not cause any pain and usually require no treatment. Unfortunately, these craze lines sometimes do stain teeth with craze linesand may appear unesthetic in your smile. Teeth whitening cannot effectively remove these craze lines as they are embedded in the tooth structure. Other treatment options that can correct these structural problems may include porcelain crowns and veneers.

Shown below is a case where the six front teeth exhibit some craze lines and some irregularity in the position. Placing four porcelain veneers and two porcelain crowns can instantly correct the colour, the alignment and the surface as well.

Before Treatment: Teeth With Craze Lines
teeth with craze lines before

After: Four Porcelain Veneers and Two Porcelain Crowns
teeth with craze lines after

Teeth with Hypocalcification/ FluorosisTeeth with Hypocalcification

As mentioned previously, teeth with fluorosis have tiny white streaks and specks throughout the surface of the enamel. These are evidence of hypocalcification of the tooth structure, which may be caused by excessive exposure of fluoride during teeth development. Teeth whitening will not remove these tiny white streaks and specks but can brighten up the yellow part of the tooth structure.

Teeth with Uneven arrangement and Wear and/or Different restorations

Teeth with uneven arrangement/wear and/or had different restorations (fillings, old crowns) can give you the appearance of an unattractive smile. Because light reflects off the tooth structure at different angles and off different materials, sometimes the teeth with such arrangement will give you an optical illusion or accentuate the uneven colour and texture across the smile. In these cases, dental treatment such as orthodontic treatment followed by porcelain veneers and/or porcelain crowns may be some dental options to consider. Realigning the teeth and placing porcelain veneers or crowns not only improve the position of the teeth but also give you a nicer appearance with better surface lustre and colour. Teeth whitening would not be able to correct the position of the teeth nor the surface lustre.

Before: Teeth With Uneven Wear & Arrangement                                                                  

before picture: uneven teeth

After: Four Porcelain Crowns
after picture: four crowns

Before: Teeth with uneven arrangement & an old crown                                                   
before picture: old crown
After: Two Porcelain Crowns
after picture: two porcelain crowns

It is my hope that this article will serve to educate some of you on the types of teeth whitening systems available and whether you may be an ideal candidate for teeth whitening. In any case, it is best to consult your dental professional for your dental conditions, as everyone’s situation is unique. I hope you will find the information helpful. Best of luck in your search for your pearly whites!