Frequently Asked Questions (FAQ) on Whitening Teeth


What methods are there to whiten teeth?

There are different methods of whitening teeth, depending on the cause of the discoloration:

Category Cause Remedy
Extrinsic Smoking, coffee, tea, red wine, chromophilic bacteria, chlorhexidene mouth wash, betel nut or tobacco chewing Polishing
Extrinsic Single tooth - has had root canal treatment Bleach/crown/veneer
Intrinsic Developmental from tetracycline, lead or excess fluoride, Yellowing with time - part of aging! Bleach/veneers

How do you prevent teeth from staining?

How easily stains on teeth are removed depends on the smoothness of the tooth surface. Rough tooth surfaces will make it more difficult for you to remove the stains by tooth brushing.

Acidic food like citrus fruits, pineapples, fruit juices, carbonated drinks, yogurts, vinegar-based salad dressings etc. cause superficial etching of the tooth, producing a microscopically rough surface. Should you consume tea, coffee or red wine or other staining food or drinks, or smoke immediately after then these stains get into the rough surface and slowly build-up over time.

To reduce staining of teeth, give about 30 minutes after acidic food before consuming tea or coffee or even smoking! This allows time for the calcium and proteins in saliva to fill these acid roughened areas, so that any stain that does form occurs superficially and is therefore, easier to remove by tooth brushing. Otherwise, repeated cycles of stain deposits directly onto the freshly etched tooth surface will result in rapid stain accumulation that is difficult to remove (see below. More heavily stained teeth will require polishing at the dentist to restore your sparkling smile!

Natural smmoth enamel surface
The tooth enamel surface is naturally smooth.
Stains accumulating on rough etched tooth enamel surface
Acidic foods etch the enamel surface and stains may be deposited directly onto the roughened surface.
Saliva deposits over the stain, entombing it.
Over the next 30 minutes, calcium and saliva proteins deposit over the stains making it difficult to brush off.

How is bleaching performed?

Bleaching can be used to whiten teeth where the by darkening of the teeth is from intrinsic causes. There are two main methods used:

Tray (Home) Bleaching

This technique typically utilizes a 10% carbamide peroxide bleaching gel that is squeezed into a tray that fits over the teeth. It is either worn during the day or overnight. The effectiveness of this system depends on the dose and contact time of the bleaching agent has with your teeth.

Over-the-counter systems are economical and provide standard-sized tray. As these standard-sized trays adapt poorly to the teeth, most of the bleaching gel tends to be washed out by the saliva, therefore, it is often reported not to work.

A custom fabricated bleaching tray made by your dentist on the other hand fits your teeth snuggly, therefore, the bleaching gel is held in contact with your teeth more effectively. Typically 2 weeks of daily overnight tray bleaching should produce a whiter smile.

Tray for bleaching
Clear plastic custom-made upper and lower bleaching tray.
Bleaching tray seated onto teeth
Bleaching trays seated over upper and lower teeth.

Chairside Bleaching

This is done by the dentist using a stronger bleach than used in the tray system. The bleaching gel is placed onto the teeth after protecting the gums.

Gums are protected with a barrier (white) then bleach (red) is placed onto the tooth surface

There are different ways of activating or accelerating the bleaching process, usually by some method of heat generation. Heat sources include the use of various types of lights, ultrasonics or lasers. The advantage of chairside bleaching is its immediate results compared with home bleaching. Two bleaching sessions may sometimes be required.

Some commercial products style themselves as 'power bleach' techniques, to imply they are more effective than their competitors, and perhaps, justify their higher cost. On the whole, however, independant studies show little difference with the different systems, whether heat of any sort is used or not. They all work!

Miscellaneous Methods

Paint-on bleach, whitening toothpaste and bleaching strips are now available to cash-in on the quest for whiter teeth. These all can potentially work but users often report no noticeable difference. This is because of the very limited contact time these products have before saliva dilutes and washes the bleach away. At least the manufacturer's are smiling!

For extrinsic stains following root canal treatment, where the tooth characteristically becomes darker than the rest, single tooth bleaching inside the crown of the tooth, known as "intracoronal bleaching" or ""walking bleach" can be performed to restore the tooth's colour to match the other teeth.

Intracoronal Bleaching

Intracoronal bleaching diagram

Following root canal treatment, bleach is placed into the crown of the tooth through the access hole made to perform root canal treatment (hence the term intracoronal bleaching). The bleach is sealed in and left for at least 3-4 days, then removed. If the colour has not been restored, fresh bleach is inserted and left for another 3-4 days.

How much whiter can bleaching get my teeth?

The bleaching effect on each person is different, and it also depends on the cause of the discoloration. Generally the whitening effect will look more dramatic when you start off with darker teeth than if you already have lighter coloured teeth. Studies indicate that success with bleaching is about 86% for tetracycline stained teeth and 98% for others.

VITA shade guide used to monitor color changes of bleaching teeth

The most commonly used shade guide, known as the Vita Classic shade guide (left), is often used to monitor the effects of whitening. When the shade tabs are arranged from light to dark, or to use the technical term, arranged by 'value', the whitening that is achieved is usually 6 to 10 tabs lighter than the start shade.

⚠ Warning: The colour of fillings and crowns are unaffected by bleaching, whereas teeth will whiten. Therefore, any visible fillings in the front teeth will become more obvious, and consequently require replacement to a lighter colour to blend in with the whiter teeth.

Are there any side effects of bleaching?

There does not appear to be any long term side effects of ingesting the tray bleaching gel. The stronger chairside bleach can "burn" the gum if it leaks through the barrier, which sometimes occurs. There is momentary discomfort, but it should heal uneventfully.

Soreness of the gums is quite common, and thermal sensitivity affects approximately 2/3 of persons following bleaching. Some also complain of a metallic taste for a few hours following tray bleaching. All these side effects are transient and should go off after cessation of bleaching.

After bleaching, how long does the whitening last?

Immediately following bleaching, there is a slight darkening of about a half shade. This is termed the 'rebound' effect. Hence, it is usually advised to whiten the teeth a touch more than the intended, to overcome the rebound effect.

Tetracycline discolouration - 5 years after bleaching upper teeth only

If you follow instructions and avoid smoking or foods that cause extrinsic staining of teeth for 48 hours following bleaching, studies indicate that the whitening effect should last approximately 3 years.

How do veneers whiten teeth?

Veneers are a thin layer of either porcelain or composite resin that are bonded onto the front surface of the tooth. These veneers are custom made and can be made whatever colour you want . so if you want whiter teeth, whiter tooth shade veneers can be made.

Porcelain veneers are colour stable, whereas composite resin materials darken over time. Usually a thin layer of the tooth is shaved off to make space for the veneer, otherwise, the tooth will look too bulky.

If a tooth is mildly rotated or is further in compared with the adjacent teeth, veneers can also be used to give the illusion that the teeth are nicely aligned by bulking it up to the level of the adjacent teeth.

Tooth reduction for veneers

Bleaching is the more conservative (and economical!) method to achieve whitening. Veneers would normally be used where bleaching does not produce the "whiteness" wanted, or the tooth shape needs to be changed, or there are developmental patches that veneers can hide.